Envenom; poisonous desert animals

48

description

Documentary of naturally occuring toxic delivery systems.

Transcript of Envenom; poisonous desert animals

Page 1: Envenom; poisonous desert animals
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ENVENOc

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piled by m

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published by m. hill for gr 601 type systems

taught online by carolina de bartolo spring 2009

academy of art university, san francisco, ca

printing by m. hill with an hp 9500 color printer

binding by danya winterman, the key printing and

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09 by m

. hill

bind

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, oak

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ed

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CONTENTsix 1 1 3 1 5 1 6 3 90 93

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survival the desert environment.

INTRODUCTIONTh e southwestern United States has a fascinating diversity of vegetation

and wildlife, much of which has evolved to survive under very hostile

environmental conditions. For the first time visitor from a more temperate

climate, the landscape appears completely alien. Cacti, mesquite trees, and

creosote bushes are the common trees to be found. Many familiar species like

oak trees have adapted to hot dry weather with smaller structures using water

conserving systems. Th e Mojave landscape is host to a variety of dreaded,

venomous and poisonous animals that have each evolved certain specialized

defense systems for their

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especially the Mojave.

A bite is a wound received from the mouth, in particular, the teeth, fangs

or sometimes the stinger of an animal, including humans. Animals often

strike or bite in self-defense, in an attempt to predate food, as well as part

of normal interactions. Other bite attacks may be apparently unprovoked.

Bites are usually distinguished by the type of creature causing the wound.

Many diff erent creatures are known to bite or to strike at humans. Th e result

of this type of injury is typically survived, unless the animal that is striking

has an exceptional envenomous delivery system.

Just exactly where are these animals to be found? How dangerous are they?

How likely are you to encounter them? What should you do if you have

a “bad encounter”? Is everything in the Southwest considered venomous

or poisonous? How can you know what is and what’s not? Encounters with

venomous or poisonous animals should be cherished and enjoyed safely

be it in the home, back yard, or when out hiking or camping. All of these

animals are an integral part of the Mojave ecosystem which is a desert

biome. The desert biome displays considerable variation,

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MOJAVE VENOM

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Th e Mojave animals live in what strikes many humans as an oppressive

environment. Th e solar energy that all green plants convert into food fuels

life here. Although in most ecosystems animals, like plants compete for food

from sunlight, here many are adapted venom use to survive as they minimize

the eff ects of too much energy from the constant solar rays.

An ecosystem is defi ned as biotic community together within its physical

environment, considered as an integrated unit. Implied here is the concept of

a structural and functional “whole” unifi ed through life processes.

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Th e ecosystem of the Mojave is characterized

as a distinctly viable unit of desert community

and interactive habitats with unique venomous

delivery systems. Th ese systems are hierarchical

and can be viewed as nested sets of open systems

in which physical, chemical, and biological

processes form interactive subsystems.

Awareness of how an animal is likely to behave

can take the fear out of an encounter and help to

keep everybody safe. Most importantly, learning

about venomous and poisonous animals can lead

surviving a potential deadly situation.

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: Insect bites may deliver infection.

: Animal bites may transmit disease.

: A bite may cause bodily injury.

: 80% of animal bites are from unknown sources.

: Any animal with claws or teeth may bite.

: An animal bite can infl ict life-long illnesses.

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average annual hospitalization for wild mojave animal bites

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ites

by Mojave anim

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1-1. This chart shows the average annual hospitalization for animal bite victims

Venomous bites are usually

named by the type of animal

that causes the wound such

as a bee sting or snake bite.

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There are few desert variables including intense

heat, varying elevation, moisture, sand and soil

composition, exposure to ultraviolet rays and

wind patterns that create specific kinds of living

conditions for many plants and animals. Nature

and habitats don’t have hard boundaries and

often overlap. Different kinds of habitats within

a short distance of each frequently occur in

the Mojave region. The vastness of the Mojave

spans the areas of lower Nevada and southern

California, Utah and the upper most part of

Arizona. The Mojave waters rarely come above

ground. Usually, the river and basin f lows can

be seen in secluded upper canyon regions. This

is prime territory for venomous animals and to

protect their rights to live, many have adapted to

develop toxins within their body systems to help

them stay and thrive in the Mojave. Many of these

animals were thought to be small in numbers

but their habitats have been revealed as hidden

and large underground territories near basin

water runoff. Here many varieties of cactus and

border on dry lakebeds. Their water conserving

habits resemble those of the animals. Spindly

shrubs and threadlike stems in plants often will

poke or prick

Ecologists use a diff erent term for each type of symbiotic relationship. In the

scenario where both species benefi t, the term mutualism applies. When one

species benefi ts and another is unaff ected that is called commensalism. Parasit-

ism is the opposite, one species benefi ts, the other is harmed. If neither species

benefi ts then ecologists call this competition. And the fourth term, neutralism

defi nes a situation where both species are unaff ected. In the Mojave region,

there are many examples

several states of the south west U

nited States.

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the mojave desert

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Th e abundance of naturally

occurring caves is one the most

common geologic features

of the Mojave. Underground

living gives animals a great

advantage of energy effi ciency.

1-2. This map shows

the overall region and

location of the vast

Mojave that spans

ran

ge

and

hab

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at an invader.

of symbiosis.

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Some animals survive only in the Mojave Desert, these are called endemic

species. Kelso Dunes, also known as the Kelso Dune Field, is the largest

fi eld of eolian sand deposits in the Mojave Desert. Like many south western

dune systems, the Kelso dunes have a number of endemic animal species.

Th e list includes at least ten species of insect, such as the Kelso Dunes Giant

Sand Treader (Macrobaenetes kelsoensis, a species of camel cricket), the

Kelso Dunes Jerusalem Cricket (Ammopelmatus kelsoensis, a stenopelmatid)

a giant Mydid fl y (Rhaphiomidas tarsalis), and the Kelso Dunes Shieldback

Katydid (Eremopedes kelsoensis), as well as several rare and venomous native

bees and wasps, and some beetles. Although not strictly endemic, several

plant and reptile species are rare outside of these dunes. One example is the

Mojave Fringe-toed Lizard (Uma scoparia), which is specialized in its ability

to actually move as if “swimming” under sand.

Some animals live throughout all the southwestern desert areas and some

are merely passing through on a migratory path. Regardless, whether living

permanently in the Mojave, staying only seasonally or fl ying by on their

way somewhere else, adaptations to the extreme climate and lack of water

must be made even if an animal is only staying for a short while. Endemic

species usually have adapted to these conditions to the highest degree. Th at

includes sophisticated methods of defense. While defense systems are varied,

they can be narrowed to the categories of venomous and poisonous delivery

systems. Th e term for venom or poison that enters the bloodstream is called

a hemotoxin. Hemotoxins, haemotoxins or hematotoxins are toxins that

destroy red blood cells (that is, cause hemolysis), disrupt blood clotting, and

cause organ degeneration and generalized tissue damage. Hemotoxins are

frequently employed by venomous animals. Th e term hemotoxin is to some

degree a misnomer since toxins that damage the blood also damage

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overall venom use

1-3. A comparison of

how venom or poison

is used by the animals

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For over a century, hypotheses regarding the primary functional utility

of venoms have been debated throughout literature. Researchers have

speculated that the development of venom delivery systems has been a key

innovation leading to the evolutionary radiation of venomous animals over

the past thirty million years. An evolutionary radiation is an increase in

taxonomic diversity or morphological disparity, due to adaptive change

or the opening of ecospace. Familiar radiations include the radiation

of land plants after their colonisation of land, the Cretaceous radiation

of angiosperms, and the diversification of insects, a radiation that has

continued almost unabated since the Devonian 400 m

illion years ago.

who m

ake venom or poison.

other tissues.

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Th e route of administration is the path by which a fl uid, poison or other ven-

omous substance is brought into contact with the body. Often the route of

administration, or delivery system can help to diff erentiate all the categories

of venomous and poisonous substances.

A substance must be transported from the site of entry to the part of the body

where its action is desired to take place (even if this only means penetration

through the into the skin). Normally, the body’s transport mechanisms for

this purpose can be far from trivial.

Th e pharmacokinetic properties of toxins are those related to the

envenomation processes of uptake, distribution, duration and even-

tual elimination are all critically infl uenced by the systemic route of the

administrator, or the animal who is envenomating for food. Toxicokinetics

is used to defi ne the systemic exposure of toxic compounds in the animals

who are prey;

1-4. The arthropod species consumes the most prey.env

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mojave prey

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measuring exposures in toxicology them

.

Many animals in the Mojave have the great misfortune of being misidentifi ed

as venomous or poisonous because of their evolved teeth, fangs, claws or other

sharply pointed body parts adapted for life in the Mojave Venomous mam-

mals may have been more common in the past. Canine teeth dated at sixty

million years old from two extinct species, the shrew-like Bisonalveus browni

and another unidentifi ed mammal, show grooves that some palaeontologists

have argued are indicative of a venomous bite. Many other scientists have

questioned this conclusion given that there are quite a few active, thriving

nonvenomous mammals (e.g., many primates, coatis and fruit bats) who also

have deep grooves down the length of their canines, suggesting that this type

of feature does not It has been suggested that there are some Mojave

animals that do not need venom because they have

become clever and eff ective enough to kill with

their tooth or claw; whereas venom, no matter how

sophisticated, takes time to disable prey. Since their

venom is manufactured to help digest prey in most

toxic animals, the reasons why animals who kill

survive or thrive may be questioned.

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arthropods

amphibians

reptiles

1918

always refl ect an adaptation to venom

delivery.

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common dangerous and non-dangerous mojave animals

venomous

tarantula

black widow

brown recluse

bark scorpion

hairy scorpion

desert centipede

harvestor ants

africanized bees

buck catepillar

gila monster

mojave rattler

coral snake

side winder

non-venomous

whip scorpion

sun spider

scupuglids

wind scorpion

desert millipede

kissing bug

banded gecko

horned lizard

king snake

glossy snake

gopher snake

poisonous

desert toad

arachnids

myriapods

insects

toads

frogs

lizards

snakes

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1-5. The common or familiar names of those Mojave animals that may envenomate or deliver toxic substances. This list compares

species that are not rare.Many non-venomous creatures closely resemble venomous creatures and are dif f icult

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By defi nition, all venomous animals produce toxins in the specialized and

unique secretory cells in a venom gland. Th e collective mix of diff erent toxins

which are produced by an animal is known as venom, which is produced and

stored by an animal until it is needed. During a bite or sting, the venom then

is activated by the delivered by injection through what is called a venomous

or venom apparatus. Th is apparatus consists of the venom producing cells.

It becomes fi rst a simple means for storing the venom, and secondly this

becomes a specialized means for the act of injecting the venom, such as

with a grooved or hollow tooth (a fang) or a stinging apparatus. Many times

this apparatus is only used for the delivery of toxins, and once injection

is performed the apparatus may not function again, fall off and or need to

be regenerated for the apparatus to effectively function.

to distinguish in nature.

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1-6. The main side ef fects of venom from Mohave animals. Envenomation may cause anaphylaxis in certain people, and the saliva and

fangs of the snake may harbor many dangerous microbial contaminants, including Clostridium tetani. If neglected, any infection may

spread and has the potential to be

Poisonous animals lack a venom apparatus to actively deliver toxins as

a defense mechanism. Instead, the survival of these species depends on the

passive, delivery of toxins. Ingesting a poisonous animal results in toxicity

and, poisonous secretions from animals such as toads or frogs may be

absorbed through the skin, resulting in toxic delivery.

Th e toxins in poisonous animals may be produced by the animal, or they

may be acquired by accumulation from the environment, primarily through

the food chain. Th ese toxins are often secondary metabolites of ingested

compounds. Poisonous animals obviously must have resistance to the toxins

to ensure their survival. So they must ingest the substances (usually found

in Mojave plants) that they use as precursors to

produce their toxins; otherwise they may loose

their toxicity. Defi ning what is “venomous” or

“poisonous” is often diffi cult, simply because

humans are not usually the intended victim.

As they are not the typical food source for the

animal, so their toxins would be wasted. For

example although all spiders produce venom

that allows them to immobilize or kill their prey,

digesting a human

clincal effects of envenomation

would be im

possible.

a fatal situation.

Neurotoxins prevent neurons

from communicating with

each other. Neurons function

using chemical messengers

known as neurotransmitters

that regulate body functions.

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Many venomous animals, especially insects are

able to lift twenty times their own body weight

and quickly move distances that are many times

greater than their own length. Th is is not because

they are strong but because they are so small.

Muscle power is proportional to its cross-sectional

area. Because the mass (the insect’s body), that is

moved is in proportion to its volume and the fact

that they also have a better leverage system than

humans do, they may jump remarkable distances

especially during an envenomous strike.

Flight has allowed the insect to disperse, escape

from enemies, environmental harm, and colonise

new habitats within the Mojave region. One of

the insect’s adaptations, fl ight mechanics, diff er

from other fl ying animals because their wings are

not modifi ed appendages. Fully developed and

functional wings occur only in adult insects. To

fl y, gravity and drag (air resistance to movement)

has to be overcome. Th e high daily temperatures

in the Mojave make most insect fl ight dependent

on cooler night temperatures. Most of the remote

water is underground, and Mojave animals can be

found near or around these resources. Th e arthro-

pods of the Mojave are the largest food source for

all animals there, including for themselves. Th eir

habitats are typically found near runoff areas of

washes found close to basins or groundwater.

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Insects are the only group of invertebrates to have developed fl ight. Th e evolu-

tion of insect wings has been the subject of much debate. Some proponents

suggest that the wings of these creatures are para-notal in origin while others

have suggested they are modifi ed gills. In the Carboniferous age, the area of

this specifi c region in the Mojave desert hosted super sized insects. Finding

gigantic insects has been found consistent with high atmospheric oxygen.

Th e amounts of oxygen present in the atmosphere found from the researched

ice core samples ranged as high as 37% compared to the current 21%. Most

groundwater in the Mojave region is known to have higher environmental

oxygen than any other water found on the surface, such as ponds, creeks and

the rainy season accumulation of road w

ater run off .

A distinctive feature of desert dragonf lies is their use of two pairs of wings

instead of one pair. Th is refl ects their ancient origin. As such, understand-

ing the coupling between their fore and hind wings might shed light on

the evolution of f light based on four wings to that based on two. The

dragonf ly is not venomous or poisonous, but is prey for arthropods and

amphibians. Female dragonf ly lay eggs in or near water, often on f loating

or emergent plants. Tethered dragonf lies can be measured for 3d wing

kinematics and vertical forces. Kinematics and envenomation are both

survival diversif ications. Damselfl ies or the suborder Zygoptera are often

confused with dragonfl ies, but are distinct. Most

damselfl ies hold their wings at rest together above

the torso or held slightly open above such as in

the family Lestidae, whereas most dragonfl ies at

rest hold their wings horizontally or occasionally

slightly down and forward. Also, the back wing

of the dragonfl y broadens near the base, caudal

to the connecting point at the body, while the

back wing of the damselfl y is similar to the front

wing. Th e eyes on a damselfl y are set apart and in

most dragonfl ies the

Two dimensional mechanism

of insect fl ight has a natural

three dimensional extension

where the pairs of vortices are

replaced by vortex rings.

eyes touch.

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Th e overall relationships of the venomous

and poisonous animals that are thriving in the

Mojave desert to all of the other animal groups

tends to remain unclear. Evidence has emerged

favoring closer evolutionary ties with insects to

the crustaceans. In the Pancrustacea theory, for

example, insects, together with Remipedia and

Malacostraca, make up a natural clade known as

the scientifi c classifi cation of the living and fossil

organisms. It is possible that the venomous and

poisonous traits may have been fi rst established

in early dissolved oxygen

Most of the food of a venomous animal is ingested in the form of macromol-

ecules and other complex substances such as proteins, polysaccharides, fats,

and nucleic acids which must be broken down by catabolic reactions into

smaller molecules of amino acids or simple sugars. All of which depend on

the waste cycles of oxygenation. All before being used by cells of the body for

energy, growth, or reproduction. Th is breaking down process is known as

digestion and is critical to producing venom. Generally speaking, venom of

newborn and small juvenile creatures appears to be more potent than that

adults of the same species. Th e bite from a snake that has not fed recently such

as one that has just emerged from hibernation is more dangerous than that of

one that has recently fed because it has more venom to inject. Venom glands

must replace venom lost with each strike or bite, and replacing venom takes

time. Th is requires protein.

Organic wastes are the remains of any living or

once-living organism. Most of the venomous and

poisonous creatures are key players in the waste

cycle in the desert. Organic wastes that can enter

a body of water include leaves, grass clippings,

dead plants or animals, animal droppings, and

or other sewage. Organic waste is decomposed by

bacteria; these bacteria remove dissolved oxygen

from the water when they breathe. If more food

(organic waste) is available for the bacteria, more

bacteria will grow and use oxygen, and the dis-

solved oxygen concentration

rich waters of the early M

ojave desert.

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ARTHROPODArthropods are the most diverse group of animals on earth and comprise

more than 85% of all living animal species. Th is fascinating group of animals

features external skeletons (or exoskeletons), segmented bodies and several

jointed legs and feet. Familiar members of this enormously large phylum

include spiders, centipedes, scorpions, crabs, and all of the insects.

Arthropods are animals belonging to the Phylum Arthropoda meaning the

greek words arthron, “joint,” and podos “foot,” which together they mean

jointed feet, and include the insects, arachnids, and crustaceans. Th e cuticles

of crustaceans are also biomineralized with calcium carbonate. Th e rigid

cuticle inhibits growth, so arthropods replace it periodically by molting.

Th e arthropod body plan consists of repeated segments, each with a pair of

appendages. Enabling them to become the most species-rich members of all

ecological guilds in most environments. In the Mojave, they make up more

than 80% of all described living species, and are one of only two groups very

successful in dry environments. In the Mojave, their sizes have a wide range.

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Arthropods’ main internal cavity is a hemocoel,

which accommodates their internal organs and

through which their blood circulates. Th ey have

open circulatory systems. Like their exteriors

the internal organs of arthropods are generally

built of repeated segments. Th eir nervous system

is “ladder-like”, with paired ventral nerve cords

running through all segments and forming paired

ganglia in each segment. Th eir heads are formed by

fusion of varying numbers of segments, and their

brains are formed by fusion of the ganglia of these

segments and encircle the esophagus. Th e respi-

ratory and excretory systems of arthropods vary

depending as much on their environment as on

the subphylum to which they belong. Th eir vision

relies on various combinations of compound eyes

and pigment pit ocelli. In most species the ocelli

can only detect the direction from which light

is coming, and the compound eyes are the main

source of information, but the main eyes of spiders

are ocelli that can form images and, in a few cases

can swivel to track prey. Arthropods also have

a wide range of chemical and mechanical sensors,

mostly based on modifi cations of the many setae

(bristles) that project

Arthropods’ methods of reproduction and development are diverse and is

dependent on migration of other arthropod communities. All Mojave ground

species use internal fertilization, but this is often by indirect transfer of the

sperm via an appendage or the ground, rather by direct injection. Aquatic

species use either internal or external fertilization. Almost all arthropods lay

eggs except for

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the Mojave region.

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major areas of venomous arthropod populations in the mojave

arachnids

myriapods

insects

Pigment pit ocelli is that

external patch or patches

of pigment and photoreceptor

cells organized in either

a fl at disk or a pit near the

head of an animal.

2-1. This map depicts

the larger populations

of venomous arthropod

communities living in

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through their cuticles.

the scorpions.

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Th e most conspicuous specialization of segments is in the head. Th e major

formal groups or orders of the Mojave arthropods are the arachnida, insecta

and diplopoda. Working out the evolutionary stages by which all the diff erent

combinations of structures of the arthopods could have appeared is so diffi cult

that it has long been known as the “Arthropod head” problem. For those

creatures with toxic delivery systems, the function of the venom glands is the

major area of study. Th e head is typically where venom delivery systems need

to originate and for the arthropod this region displays

Th e original arthropod appendages were most

likely biramous, or having an upper body that

works as a gill while the lower body was probably

used for walking. In some segments of all known

arthropods the appendages have been modifi ed

to perhaps form gills, mouth-parts, antennae for

collecting information, or claws for grasping.

Arthropods are each equipped with a unique set

of specialized tools with a mandible for eating

with a claw, two sets of antenna plus four pairs

of walking legs and four pairs of swimmerettes.

In many arthropods, appendages have vanished

from some regions of the body, and it is common

for abdominal appendages to have disappeared or

be highly modifi ed with ar

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many varied and unique structures for delivery of venom

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varied pods.

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2-2. The toxic strike ef fects from the three major categories of Mojave arthropods. The most dangerous group are the arachnids which

include the infamous Black Widow spider, otherwise

Typical arthopod heads possesses a pair of antennae; eyes; mandibles,

labrum, maxillae and labium. Lying above the oesophagus is the brain

or supraesophageal ganglion, divided into three pairs of ganglia: then the

protocerebrum, deutocerebrum and tritocerebrum lining up from front to

back. Nerves from the protocerebrum lead to the large compound eyes, then

to the labrum and stomatogastric nervous system. Circum-oesophageal

connectives lead from the tritocerebrum around the gut to connect the

brain to the ventral ganglionated nerve cord: nerves from the first three

pairs of the upper ganglia lead further on to the mandibles,

clinical effects of envenomation from mojave arthropods

known as the w

orlds most deadly spider. a

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process of envenomation.

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Th ere are two diff erent types

of excretory systems in the

arthropod. Th e end product

of biochemical reactions that

metabolise nitrogen is so toxic

that it needs to be diluted as

much as possible with water.

Ammonia is eliminated via

any permeable membrane.

The position of the arthropod mouth and

the circum-oesophageal connectives allows

the distinction to be made between the oral

structures and it should be borne in mind

that these structures can move around during

development and are critical for the

maxillae and labium

, respectively.

Page 20: Envenom; poisonous desert animals

Living arthropods have paired main nerve cords running along their bodies

below the gut, and in each segment the cords form a paired ganglia from

which their sensory and motor nerves run to other parts of the segment.

Although the pairs of ganglia in each segment often appear physically

fused and they are connected by relatively large bundlednerves, which give

arthropod nervous systems a ladder-like appearance. The brain is in the

head, encircling and mainly above the esophagus. It consists of the fused

ganglia of the acron and one or two of the foremost segments that form

the head, for a total of three pairs of ganglia in most arthropods. But there

are only two in the portion of chelicerates, which do not have antennae

or the ganglion connected to them. The ganglia of other head segments

are often close to the brain and function as part of it. In insects these

other head ganglia combine into paired subesophageal ganglia, under and

behind the esophagus. Spiders take this process a step further, as all the

segmental ganglia are incorporated into the subesophageal which occupy

most of the space in the cephalothorax or the front portion known as the

super segment.

Various groups of Mojave arthropods have independently developed

a diff erent system. Th e end product of nitrogen metabolism is uric acid which

can be excreted as dry material; Malphigian tubules fi lter the uric acid and

other nitrogenous waste out of the blood in the hemocoel, and dump these

materials into the hindgut, from which they are expelled as feces endowed

with precious micronutrients

All the arachnid bodies are divided into two

main parts. Th ese are referred to as the head or

the cephalothorax and the abdomen. Th e head or

cephalothorax contains simple eyes, mouth parts,

sensory organs, and paired limbs. Th e fi rst pair

of limbs, called chelicerae, may form pincers or

fangs. Th e second pair, called pedipalps, may

serve as pincers, sensory appendages, or legs. Th e

rest of the cephalothorax usually has four pairs of

walking legs. Th e abdomen contains the genital

opening and book lung, or modifi ed gills, used

for gas exchange and oxygenation.

Scorpions are those arachnids that are quickly

recognized by their segmented, curved, stinging

tails and their large pedipalps, or pincer looking

extremities. Th e body of a scorpion is composed

of a short, compact cephalothorax with an very

elongated and segmented abdomen area which is

referred to as the mesosoma. Th e feeding parts

or appendages and the chelicerae, pedipalps, and

segmented legs all attach to the larger cephalot-

horax. Th e chelicera is the most developed and

envenomous section

ar

th

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39

arac

hn

ids location of the chelicerae in the arthropod

dorsal view

ventral view

chelicerae

featured in the arachnid.

2-3. The chelicerae is one of the anterior pair of the appendages

of an arachnid often specialized as fangs or often referred to as

their pincers or

env

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38

for Mojave plant life.

co

nn

ecti

ng

pai

rs

hind pincers.

Page 21: Envenom; poisonous desert animals

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4 1

Chelicerate head structures diff er considerably from those of the man-

dibulates, or those head structures found in other arthropods like the

myriapods and insects living in the Mojave. They possess eyes and

a single pair of grasping appendages innervated from the brain, plus

a dense fibrous structure known as a labrum. Behind the mouth lies anoth-

er pair of mouthparts, then the pedipalps, and behind them lie the series of

walking limbs. In chelicerates the leg bearing segments are fused with the

anterior segments to form a prosoma so that in living arthropods a distinct

head actually only exists in the mandibulate structure.

Toxicologically, there is far more diversity in spider venoms than in the

venoms of myriapods, scorpions and most insects so that the correct iden-

tifi cation of spider bites has special signifi cance. Spiders are rarely correctly

identifi ed by bite victims or sometimes even their physicians and are readily

transported out of their native range. Making diagnosis diffi cult, and in some

cases healing is compounded

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Members of the spider genus Loxosceles Sicariidae are most commonly known as the brown recluse spiders

Many spiders living on the Mojave are misidentifi ed as Loxosceles. Th ese spiders are rather nondescript

with uniformly colored abdomens that can vary from a tawny to dark brown. Th e legs and body are

covered with fi ne hairs and they have small leg spines. On the the fi rst body segment, to which the legs are

attached there is a characteristic darkened violin pattern. Brown recluse spiders make a protective silken

retreat that occasionally can entangle prey, but they are more often hunters that prowl for prey. Th ey

can be found in high numbers in human structures such as shacks or even abandoned mine shafts in the

desert. Th eir nocturnal wanderings place them in contact with humans. Similar to black widow spiders,

brown recluse spiders usually bite only when they become trapped next to the victim’s skin. Bites occur

either when sleeping humans roll onto the spider or put on clothes into which the spider has crawled.

Sometimes a bite from a brown recluse spider can go unnoticed, or maybe feel as slight as simply a tiny

pinprick. However, after only a few hours, there is ensuing severe pain, erythema, and localized tissue

necrosis due to the venom’s proteolytic enzymes. Th ese

by mistreatm

ent.

a venomous spider

smaller body m

asses.

2-4. Depicting the violin pattern on the head or the cephalothorax.

A localized envenomation will have a necrotic

ulcerated lesion or open sore. If this occurs near

a systemic artery, the bite can be life-threatening.

Within ten minutes of venom injection, there

is a constriction of capillaries around the site

of the bite indicating that the blood has been

envenomated. Potential renal failure is a concern

especially for

related enzymes are the com

ponents of the venom.

Page 22: Envenom; poisonous desert animals

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Myriapoda is a subphylum of the arthropods that

contain the millipedes and those similar creatures

centipedes. Th is group contains thousands of the

species, all of which are terrestrial. Although their

name suggests they have myriad or 10,000 legs,

myriapods actually range from having over 750

legs to having fewer than ten legs. Th ey all have

a single pair of antennae and simple eyes.

Although not generally considered dangerous to

humans there are many myriapods that produce

secretions, often containing benzoquinones which

can cause blistering and discolouration of

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43

the skin.

myr

iapo

ds

Using powerful jaws located immediately

under the head they grasp and kill their prey

by injecting venom in to surface areas. Th e bite

of most centipedes is incapable of penetrating

human skin. But some can squirt their fl uids

over distances of several inches. Th e bite of

the giant desert centipede is quite painful, but

it is not considered particularly dangerous.

Th e venom causes both pain and swelling, and

often red streaking called lymphangitis. Th ere

may be systemic symptoms including anxiety,

fever, dizziness, palpitations, and nausea. Skin

breakdown may occur at the site of a bite but it

usually heals without the need for skin grafting.

Many other long-termed illnesses happen with this venom

.

Page 23: Envenom; poisonous desert animals

Th e most common stinging animals are in the insect order Hymenoptera

meaning “veil wings”, which includes the bees, wasps and ants. Th e most

primitive Hymenoptera possess ovipositors to insert eggs into plant tissue. In

some parasitic groups this structure and glands associated with it have been

modifi ed to inject venom to paralyze other insects which are used as food by

the developing larvae. (Th ese parasitic wasps comprise the largest number

of species in the Hymenoptera, and are extremely benefi cial to agriculture

as biological control agents of agricultural pest insects.) Th e stings of these

parasitic wasps are often not very painful to humans due to low toxicity.

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45

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4 4

Bees, wasps, ants, and even caterpillars-sometimes it seems that everything

with more than four legs stings. Fortunately, most insects don’t sting, and

most insect venoms are not particularly dangerous to people. Th e greatest

risk that we face from insect stings is anaphylaxis. Th is is a severe allergic

reaction that can be triggered by even minute amounts of proteins in a ven-

om. Anaphylaxis is most common in people who have been sensitized to the

protein that triggers the reaction, usually by previous exposure from a sting.

Given the tremendous diversity of insects and relatively low medical risk

from most insect stings, this book covers only a few of the more signifi cant

and Mojave members of this class.

Insects are a class of arthropods that have three main body sections. Begin-

ning with the head, thorax, and abdomen. Th ey have three pairs of legs that

attached to the thorax, and usually two sets of wings. Th e insect life cycle is

either three-part (egg, nymph, adult) or four-part (egg, larva, pupa, adult).

Insects account for most of the biomass on earth and are represented by over

a million known species, divided into 32 orders; it is thought that there may

be as many as 10 million species. Th e most recently discovered order of the

insects are the Mantophasmatodea, or “gladiators,” that were fi rst described

Th e toxicity of the wasp venom is so low that

it is not considered an envenomous design for

the defensive sting. Th e insect, like bees, will

usually fl ee rather than sting when disturbed. Th e

sting has become the specialized defensive tool

in other groups of insects and the ants and bees

which evolved from these insects. Most wasps and

bees are solitary, and do not defend their nests

though they will sting in defense if caught. It

is in the social Hymenoptera that we see active

defense of the nest, and it is mostly these groups

that cause medically injury and signifi cant stings,

although a few large species of stinging bees can

cause painful and potentially serious stinging if

captured or perhaps stepped on.

in Africa in 20

02.

inse

cts

Page 24: Envenom; poisonous desert animals

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46

Th e commonly active components of honey bee venom include enzymes,

other smaller proteins and peptides, and amines. Among the principle small

proteins and peptides are melittin, apamin, and peptide. Th e melittin is what

constitutes about 50% of the venom dry weight; it hydrolyzes the cell mem-

branes causing changes in permeability and is most responsible for the pain

associated with the sting. Peptide is also known as mast cell degranulating

peptide and causes mast cells to release histamine as they degranulate, and

sets up an infl ammatory reaction. Enzymes include phospholipase (11% of

dry weight), which is non-toxic when pure but in concert

phys

iolo

gy

of

the

stin

g

Most fatalities from bees and wasps stinging

occur in hypersensitive individuals; death is most

often induced by a single sting, and occurs most

often within one hour after the sting. Th e victim

is typically over 40 years of age and stung on the

head or neck. Most of these deaths are caused

by a respiratory dysfunction with the second

most common being anaphylaxis or immediate

respiratory arrest. Also, arteriosclerosis may be a

compounding factor. Large numbers of bee stings

can also cause death

with the m

elittin becomes a m

ajor hemolytic factor.

in non-hypersensitive individuals.

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47

Th e most common and typical dermatologic expression for honey bee ven-

om is seen as a raised white weal with central red spot of which appears

a few minutes after the sting, and lasts for about 20 minutes. Honey bee

stings can usually be defi nitively diagnosed by the presence of the detached

sting, which will remain in the wound until removed. Th ere may be swelling

or edema and the initial intense pain will last only minutes and symptoms

should resolve in a few days. Patients who have been sensitized by prior stings

may display large, local reactions including 10-50 cm edematous swellings

forming a hour post-sting and persisting for 3 days. Symptoms, especially

edema, are much more pronounced when the sting is delivered to the face and

neck. Many victims with edema and pruritis think they are allergic but these

are the typical localized symptoms of the africanized honey bee envenoma-

tion. Occasionally similar large reactions occur at sites not adjacent to the

sting site and these are considered systemic infections rather than local reactions.

Page 25: Envenom; poisonous desert animals

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48

stinging more than once.

Uniquely in honey bees amongst bees and wasps

of the workers’ stings is their ovipositor. Th ey

are barbed, and lodge in the f lesh of mam-

mals upon use and tear free from the bee’s

body, leading to the bee’s death within a few

short minutes. The sting has its own gangli-

on and with it continues a sawing action into

the target’s f lesh and then releases bee venom

for several minutes. The question is how such

a trait could have evolved, when it is of such

an obvious disadvantage to the individual is

resolved when one realizes that mammalian

predators can easily destroy the entire colony if

not repelled; if the colony is destroyed, a worker

being sterile, will die without offspring, so only

through defense of the colony can she see to it

that her genes are passed on. The barbs ensure

that a honey bee’s attack is only suicidal if the

attacker is a mammal as they can sting other

bees (in inter-colony raids) repeatedly. Thus,

under natural conditions, the suicidal aspect of

the honey bee sting’s barbs only come into play

in the event of an attack which threatens to wipe

out the entire colony. The stinger of nearly all

other bees and wasps is not barbed, and so can

be used to sting mammals repeatedly with the

only exceptions being yellowjacket wasps and

the Mexican honey wasp who have barbs that

are so small that they do not cause the stinging

apparatus to pull free;

stin

gin

g t

o t

he

dea

th

Page 26: Envenom; poisonous desert animals

poisonous and potentially dangerous.

AMPHIBIANAmphibians are cold-blooded vertebrates with typically smooth skins; they

hatch as aquatic larvae with gills, then transform into air-breathing adults

with lungs. Th e class Amphibia includes frogs, toads, salamanders, and newts

and most are capable of living on land or in water. Th ere are nearly 5,000

species of amphibians worldwide, and a signifi cant number of these are

poisonous, such as the well-known poison arrow frogs of Central and South

America. Th e poisons in amphibians are usually found in the skin or skin

secretions. Frogs and toads are subdivided within the class Amphibians into

an order called the Anura. Of the amphibians in the Mojave desert, only two

species of toad Bufo marinus and Bufo alvarius are consideredc

hapter th

ree

Page 27: Envenom; poisonous desert animals

hab

itat

s an

d r

elat

ion

ship

s “Frog” may be used for any

anuran, whereas, “toad”

is used for members of the

genus Bufo as well as for

frogs of similar body form.

am

phibia

n

53

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52

will take over their spaces.

Although nearly everyone knows one when they

see one, the term toad has very little taxonomic

usefulness, even though it is still commonly used

to describe the anurans that are not frogs. Th e two

poisonous species of toads in the United States are

both members of the large family of “true toads”

called Bufonidae. Th e giant toad also called the

marine toad or cane toad, or Bufo marinus, is

a familiar native to Texas but is endangered and

rarely seen. Th e Desert toad, or Bufo alvarius

is formerly called the Colorado River toad, has

been popularized by songs and stories about

“toad-licking.” Th is toad is native to and found

only in the southwestern Mojave.

Spadefoot toads are also anurans, but they are

not in the true toad family of Bufonidae. Th ey

get their name from the keratinous bone on their

hind feet that forms a metatarsal “spade” used for

burrowing backwards in wet soil. Th ey use this

to dig rapidly backward, circling as they descend

into deep desert tunnels. Th ese burrows are often

shared by other desert creatures, and sometimes

in the intense dry heat predators

the closely related cane toad Bufo marinus.

No reports of human deaths from Desert toad poisoning have occurred in

the Mojave, but about 40-50 pets, mostly dogs, die every year from ingesting

or even just mouthing this toad, a clear testament to the potency of the this

poison. Th e milky secretions from the glands of the Desert toad contain over

26 biologically active compounds, including potent cardiovascular toxins

known as bufodienolides and another substance called 5-meo-dmt, which

produces psychoactive eff ects.

Th e cardiotoxic bufodienolides, including bufogenin and bufotoxin are

structurally similar to the cardiac drug called digitalis that is purifi ed from the

foxglove plant. Th e bufodienolides are well-absorbed in the gut and ingesting

crude toad poison (and even topical exposure from carelessly handling toads)

may result in severe headache, nausea and violent vomiting, irregular heart

rhythms, blurred vision, and seizures. Severe toxic reactions including death,

have occurred after mouthing and ingesting the nodes of

Page 28: Envenom; poisonous desert animals

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phibia

n

55

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54

3-1. The most identifying characteristic of Bufo alvarius is the

presence of large granular glands that look like nodes. This figure

highlights the area where parotoid gland is in location to other

nodes found on the legs and

bufo alvarius

Bufo alvarius requires a minimum overall body length of only three inches

for sexual maturity although breeding adults continue to mature to grow

to be seven inches in length. This desert dweller is of stout build with a

squat body and a f lat broad head. The skin is smooth and leathery, sparsely

covered with pale orange warts or nodes. The belly is creamy colored and

usually unmarked. There are one to four prominent round white warts at

the corner of the mouth. The granular glands are specialized multi-cellular

concentrations of tissue. The most prominent of these is the pair of large

kidney-shaped parotoid glands located one on each side of the neck, over

and behind the tympanum. Enlarged and elongated glands on the outside

of each hind leg, between the knee and thigh, are called femorals. Simi-

larly, the tibeals are long glands, or a line of shorter ones, that run the full

length between the knee and ankle. An additional gland concentration can

be found on each of the stubby forearms where they are usually are orange

or creamy colored. On the Desert toad all of these glands

The presence of the potent hallucinogen 5-meo-dmt in the secretions

of Bufo alvarius has led some people to ingest the skin of the toad in an

attempt to experience the psychoactive and/or psychedelic effects. Rather

than the expected hallucinations, the usual result is a violent, severe type

of poisoning intoxication comparable to a digitalis overdose. The cardio-

toxic bufodienolides in the toad secretions are well-absorbed in the stomach

whereas the hallucinogenic 5-meo-dmt is typically inactivated in the gut

by monoamine oxidase (unless the person is taking a certain monoamine

oxidase inhibitor) and never makes it into the circulation or to the brain.

Ingestions of the poisonous secretions are therefore dominated by the largely

profound effects of the cardiotoxic compounds, leading to nausea, violent

vomiting, severe headache, and potentially low blood pressure and death by

cardiovascular collapse. Because 5-meo-dmt is inactivated in the gut, there

is virtually no possibility of having a “psychedelic” experience by taking

in or eating, otherwise ingesting the secretions, which explains why toad

licking is not a very clever or popular recreational drug.

Interestingly, the hallucinogenic compound 5-meo-dmt is heat-stable

whereas the cardiotoxic bufodienolides are not. The integrative medicine

physician Dr. Andrew Weil has reported that the crude poison from Bufo

alvarius can be collected, dried, and smoked. The bufodienolides become

inactivated by the heat, and the 5-meo-dmt still remains pharmacologically

active. Along with Weil’s other ethnopharmacological research the fact that

the tryptamine derivative 5-meo-dmt is found only in Bufo alvarius and

not in other toads led to the hypothesis that the preColumbian peoples

of the New World may have smoked the dried secretions from this toad as

a certain kind of ritual intoxicant.

parotoid gland

psyc

ho

acti

ve

pois

on

secrete milky-w

hite Bufo poison.

feet of Bufo alvarius.

Page 29: Envenom; poisonous desert animals

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phibia

n

57

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56

With their large size and frequent habit of simply

sitting nonchalantly out in the open as they wait

for something edible to happen by, Desert toads

might seem to be an easy target for predators, but

these large, slow toads are very well defended.

Bufo alvarius is nocturnal and remains hidden

underground throughout the day escaping the

extreme temperatures with the strategy of lead-

ing a subterranean life. At dusk, these desert toads

leave their hidden recesses and will congregate in

those damp wet areas near springs and streams

that may be in fi elds irrigated for agriculture,

even places like temporary pools left after heavy

storms. Th e breeding season May through July is

the period of time for the greatest activity for

this Desert toad called Bufo alvarius. Large

healthy toads can be gathered after dark using

a fl ashlight and collection box or a cloth bag.

Often during the summer monsoon or stormy

season Desert toads are common nocturnal guest

visitors to human habitats near water or natural

desert vegetation. Th ey emerge after the short

summer rains in order to feed in large temporary

rain pools. During the rest of the year Desert

toads will hibernate in their underground spaces.

Th e Desert toad can be an allusive 3-2. The main side ef fects of poisoning from the two varieties of toads are typically minor unless left

untreated. Deliberate ingestion of the Bufo poison is always more harmful

clincal effects of desert toad poisoning

to any Mojave creature.

no

ctu

rn

al h

abit

s

night predator.

On land, amphibians will

feed on worms and insects like

spiders and fl ies. Each of the

amphibian species have many

diff erent feeding habits. Some

toads may feed by protruding

their long tongue. Whereas,

caecilians will kill their prey

with the help of their sharp

saw-like teeth.

100

0

50

de

ser

t to

ad

(b

ufo

alv

ar

ius)

spa

de

to

ad

(b

ufo

ma

rin

us)

de

ath

seiz

ur

e

vo

mit

ing

dr

oo

lin

g

mo

uth

ir

rit

ati

on

fr

eq

ue

nc

y o

f e

ffe

ct

(pe

rc

en

t)

Page 30: Envenom; poisonous desert animals

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phibia

n

59

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58

All amphibians breathe through their skin as such they are much more

directly affected by changes to any chemistry in the air and or the

water quality that is associated with pollution (including loss of ozone layer

in upper atmosphere). Th ey are also sensitive to fungi and diseases which can

infect them through their skin. Th ey also require aquatic habitats for their

reproduction so they are much more directly aff ected by changes in water

levels in lakes and streams either by climate or weather changes but also from

changes in human uses of water.

Because of their complex life cycles they often have to move between habitats

making them sensitive to changes in not only those specifi c habitats that they

need for food and shelter but also all the places they need to travel through

to get to these habitats. Th e desert amphibian lives in a variety of arid and

semi-arid habitats, such as brushy plains desert, semi-arid grasslands and tree

lined canyon lands. Th eir developed envenomous skills actually

According to recent surveys, many amphibians

are said to have disappeared from areas, where

they were found in abundance. In fact, some

amphibians like the Poison dart frog, California

tiger salamander and Houston toad are listed

among the endangered species while others are

already extinct. Many biologists share the idea

or opinion that climate change, global warming

and environmental pollution along with habitat

loss are all playing a detrimental role in all these

declining population of amphibians. For example

the harmful ultra violet rays of the harsh Mojave

sun aff ect the proper hatching of amphibian eggs

as they do not have

bio

-in

dic

ato

rs

Mojave regions.

protective shells.

Desert amphibians frequently fi nd their habitat

in the abundant rodent burrows. Any changes in

roads, trails, traffi c, fi res, logging and other kinds

of disturbances can all aff ect the ability of these

species to survive even in the most remote

ensure their survival.

Page 31: Envenom; poisonous desert animals

It is important to mention the role of the intense

desert sun in the evolution of envenomation.

While It has been demonstrated that species of

Amphibians that were exposed to controlled

ultraviolet rays as eggs had malformed legs, there

are some venomous Mojave animals, including

reptiles, and insects such as bees, can see into the

near ultraviolet for survival. Th ere are many food

sources such as fruits, some fl owers and seeds

stand out more strongly from the background in

ultraviolet wavelengths when it is compared with

human color vision. Some species of Scorpions

will glow or take on a yellow to green color under

ultraviolet illumination thus assisting the control

of these sometimes fatally venomous arachnids.

Urine trails of rodents can be detected using

ultraviolet light as well.

Many creatures use the ultraviolet wavelength

emissions from celestial objects as references for

navigation. A local ultraviolet emissor can disrupt

the navigation process and will eventually attract

the fl ying insect. Diff erent designs of ultraviolet

light traps are also used by entomologists to study

envenomation and the role

the

role

of

ult

rav

iole

t li

gh

t an

d e

nv

eno

mat

ion

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n

61

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60

it plays with sunlight.

Page 32: Envenom; poisonous desert animals

R EPTILEReptiles make up a group of about 8,000 species of cold blooded vertebrates

that are divided into four orders: the Crocodilia or crocodiles and alligators,

the Rhynchocephalia or tuataras of New Zealand, the Squamata or lizards and

snakes, and the Chelonia or turtles. Like birds and mammals, but unlike the

amphibians, reptiles are amniotes; during development, the embryo is simply

enclosed in an amnion, a tough, membranous sac fi lled with fl uid. Most all

reptiles are oviparous and lay eggs, although some are ovoviviparous and still

retain the eggs internally until after they hatch.

Most reptiles have three-chambered hearts, a pair of lungs, and a pair of

kidneys. Medical scientists have become interested in the unique metabolism

of many reptiles that allows them to survive, and in some cases thrive, under

dangerously harsh habitats

ch

apter fou

r

and overall conditions.

Page 33: Envenom; poisonous desert animals

Lizards are classifi ed in a suborder of Squamata called the Sauria or Lacertilia.

Most lizards are four-legged and have both external ear openings and eyelids.

Glass lizards have no true legs, but they do have ears and eyelids. Lizards

generally have dry skin and tend not to live in or near water. Many lizards can

change color at times of stress or to blend in with their environments; many

can also regenerate lost limbs or their tails. Th e largest lizards in the world

are monitors, such as the komodo dragon of Asia. At 175-310 pounds it is very

dangerous, but more often non-venomous. Th e only venomous lizards in the

world are the Gila Monster and the beaded lizard of Mexico. Th e Mojave is

the home of the largest populations of Gila Monsters in the world.

Th ere is no other lizard besides the Gila Monster in North America that

lays eggs that over winter and hatch the following year. Th e brightly colored

newborns require

major areas of gila monster habitats

ca

lifor

nia

ar

izon

a

ne

vad

a

4-1. The circles on this

map indicate the known

underground areas where

large populations of the Gila M

onster dwell.

one to three years to reach adult size.

Long and slender, short and stout, most lizards

have well developed legs, but they come in many

styles to suit their particular environment. Th eir

toes, too, may have strong claws for climbing or

digging, fringes for shimmying through sand

or even webbing for guiding and swimming in

various desert aquifers that can be several miles long.

Over thousands of years, some lizards have developed reduced limbs or lost

their limbs altogether. Th ese lizards usually burrow underground where they

have adapted to also closing their nostrils to prevent sand from getting into

them. Desert lizards inhabit scrubland, succulent desert, and oak woodland

where they seek shelter in burrows, thickets, and under rocks in locations

with ready access to moisture. Such as major groundwater resources. In fact

Gila Monsters seem

rept

ile

65

env

eno

m

64

liz

ard

s

to like water.

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20

-20

0

gr

ou

nd

wa

ter

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ll t

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ve

ls (

inc

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198

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5

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year

67

env

eno

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66

rept

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Th e name Gila refers to the Gila River Basin in Arizona, where they were once

plentiful. Recently, large populations of Gila Monsters have been discovered

hidden in massive underground caves, where groundwater is more plentiful.

Th is suggests they are successful at using their venom as survival. Heloderma

means “studded skin”, from the Ancient Greek words Helos meaning the head

of a nail or stud and derma, or skin. Suspectum comes from the describer

paleontologist Edward Drinker Cope, who suspected that the lizard might

be venomous due to the appearance of specialized grooves on pairs of their

fi nely shaped teeth.

Th e venom of Gila monsters is complex and similar to that of the elapid

group of venomous snakes, such as coral snakes. Unlike venomous snakes

Gila monsters have venomous glands in their lower jaws, rather than in the

upper jaws. Th e venom glands are modifi ed salivary glands and they produce

more than 20 diff erent toxins that can act synergistically with themselves.

Th e primary toxins in Gila monster venom are called gilatoxin, hemorrhagic

toxin, and phospholipase a2. Th ere is also a component called hyaluronidase

that causes tissue breakdown and aids in the spread of the venom away from

the bite. Gila monsters do not have fangs, but instead have grooved teeth

that are used to direct the venom into the wound by capillary action. Th ey

typically bite or inject for a prolonged time, to allow the penetration of

a suffi cient amount of venom.

Th e venom itself primarily contains neurotoxins and causes respiratory failure

in prey, although it usually causes extreme pain in humans. It also causes

a chain reaction of swelling, nausea, vomiting, and occasionally bleeding.

Fatalities have occurred, but mostly in the case of an allergy developing in

the form of anaphylaxis or respiratory failure due to the proteins contained

within the toxic mixture of

4-2. This data compares the decline in recent groundwater levels to the lizard populations of the Mojave. The Gila Monster, a venomous

animal, demonstrates a more

the decline in groundwater levels and lizard populations

all lizards

gila m

on

sters

competitive survival rate.

the

gil

a m

on

ster

the venom.

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68

rept

ile

4-3. This timetable shows how long a Gila bite victim has to experience the various side ef fects and

how long the the victim has to survive

gila monster envenomation

Pain is initially confi ned to the area of the bite. When bitten, it is important

to disengage the lizard as soon as possible. Th is may be done by placing

a strong stick between the bitten part and the back of the lizard’s mouth

and pushing against the rear of the jaw. If this doesn’t work, immersion in

water may make it release its hold. Th e brittle teeth of the Gila monster may

remain imbedded in the wound and must be removed

the envenomation.

by a medical professional.

Most lizard bites actually occur on any of the

fi ngers, or the hands, and arms when someone

is working with or trying to catch a lizard. Th e

legs and feet are also common bite sites. Th ese

bites usually occur when a person (especially

a child or a even a hiker) disturbs a lizard.

pa

in

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vo

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24

0

12

tim

e (

ho

ur

s)

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71

rept

ile

Th e juveniles typically have larger bands of pink scales than adults, although the

banded Gila monster, or h. s. cinctum, has a tendency to retain the band pattern.

h. suspectum sexually matures at 3-5 years. After egg-laying, adult Gila monsters

gradually spend less time on the surface to avoid the hottest Mojave summer heat

(although they may be active in the evening), eventually starting their winter

hibernation around November. Juvenile Gila monsters are known to eat up to

50% of their body weight in one feeding, the adults may consume up to 35%

of their body weight. When eating such large amounts they may have to only

consume three of these large meals a year.

Little is known about the social behavior of h. suspectum, but they have been

observed engaging in male-male combat, in which the dominant male lies

on top of the subordinate one and pins it with its front and hind limbs. Both

lizards arch their bodies, pushing against each other, and twisting around in

an eff ort to gain the dominant position. A wrestling match ends when the

pressure exerted forces them to separate, although bouts may be repeated over

a continuous amount of time. Th ese bouts are typically observed just before

the mating season. It is thought that those with greater strength and endur-

ance win more often and enjoy greater reproductive success.

Urban sprawl, the pet trade

and habitat destruction has

directly aff ected the process

of Gila reproduction. Th is has

resulted in legal action in

several states. It is illegal to

hunt, trap or capture any

Gila Monster.

Th e Gila monster emerges from hibernation in the

months of January or February and mates in May

and June. It is the male who initiates courtship

by fl icking his tongue to search around for the

female’s scent. If the female rejects his advances

she will bite him and crawl away. When successful

the copulation has been observed to last from 15

minutes to as long as 2.5 hours. Th e female will lay

eggs in July or August, burying them in sand 12.7

centimetres (5.0 in) below the surface. Th e clutch

consists of two to twelve eggs, with fi ve being the

average clutch. Th e process of incubation lasts

nine months as the hatchlings emerge during the

months of April through June the following year.

Th e hatchlings are about 6.3 in long, and are able

to bite and inject venom upon hatching.

30 in captivity.

env

eno

m

70

hab

itat

s an

d r

elat

ion

ship

s

when they engage prey.

Although the Gila monster has a low metabolism

and one of the lowest lizard sprint speeds, it has

one of the highest aerobic scope values among

all lizards, allowing them to engage in intense

aerobic activity for a sustained period of time. It

has also been observed that males have a higher

aerobic scope than females, presumably because

of sexual selection for a trait advantageous in pro-

longed combat. Th e Gila monster may live up to

20 years in the wild, or up to

Th e Gila juveniles typically have larger bands of pink scales than adults,

although the banded Gila monster has a tendency to retain the band pattern.

Th e Gila monster will sexually mature at the between the ages of 3-5 years.

After the female egg-laying, adult Gila monsters gradually spend less time on

the surface to avoid the hottest part of the summer, although they become far

more active during the evening

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73

rept

ile

In 2005 the United States Food and Drug Administration approved the drug

exenatide (marketed as Byetta) for the management of human type 2 diabe-

tes. It is a synthetic version of a protein, exendin-4, derived from the Gila

monster’s saliva. In a three-year study with people with type 2 diabetes, ex-

enatide led to healthy sustained glucose levels and progressive weight loss.

Th e vast eff ectiveness is due to the fact that the lizard hormone is about 50

percent identical to glucagon-like peptide-1 hormone in the human digestive

tract that increases the production of insulin when blood sugar levels become

high. Th e lizard hormone remains eff ective much longer than the human

hormone, helping diabetics keep their blood sugar levels from getting too

high. Exenatide also slows the emptying of the stomach and causes a decrease

in appetite contributing

env

eno

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72

10 ,000

0

5,000

gil

a m

on

ste

rs

year

199

9

20

01

20

02

20

03

20

05

20

06

20

07

20

09

20

08

20

04

captive

wild

current estimated gila monster population

4-4. The estimated Gila Monster population indicates that more are in captivity. The San Diego Zoo the first zoo to successfully breed

and nurture the Gila m

onsters in captivity.

to weight loss.

Th ough the Gila monster is

a venomous animal, laggard

movement combined with

slow reaction times means that

it poses little threat to humans.

Page 38: Envenom; poisonous desert animals

75

rept

ile

Snakes are long, scale-covered vertebrates with limbless bodies. Th ey also lack

eyelids and external ear openings. Along the underside of the body, snakes

have a specialized row of scales. Some families of snake retain vestigial pelvic

girdles although none have pectoral girdles. Th e bones of the upper jaw are

not fused at the snout, but can unhinge when eating. 45,000 people are bitten

by snakes every year in the us. Th ere are 11 species of rattlesnakes identifi ed

in the Mojave. Most of them occur in rocky areas but most snakebites actu-

ally occur in the Lake Mead region. Recreation and casual human activities

induce skakebites in general, and this region is surrounded by urban sprawl.

Snakes are cold-blooded and take on the temperature of their surroundings.

Th e snake shown in these images was in direct sunlight, however it was still

a bit cooler than the person holding it. Snakes warm up by lying in sunlight.

Th is increases the snake’s energy level, making it easier for the snake to de-

fend itself or make a hasty retreat. Th e large surface area of a snake’s body

allows a snake to warm up and cool down faster. Snakes will often coil their

bodies to control the amount of skin exposed to sunlight. Snakes cool down

by seeking cooler shaded areas and during very hot weather seek shelter under

rocks or underground. During long periods of cold weather, snakes often

choose to hibernate.

Some of the more common snakes seen include the highly toxic Mojave green

rattlesnake, the sidewinder rattlesnake, the California king snake, the red

racer and the gopher snake. Of these snakes, only the Mojave green and the

sidewinder rattlesnakes are

map showing location of the lake mead area

4-5. Lake Mead hosts large

areas of human recreation

communities in the Mojave.

The green snake thrives

lak

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co

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ad

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vir

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74

snak

es

dangerous and venomous.

in this region.

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100

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(pe

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rept

ile

Th e function of the rattle has been debated for centuries, but it is now clear that

it serves as a warning to anything that might harm the snake. It is a fact that

Rattlesnakes in the wild are seldom observed using their rattles but only in the

cases where they are disturbed, and they do not use their rattles to distract or

attract prey (such as inquisitive birds), or to locate other rattlesnakes.

Th e size of the rattle and its relationship to the rattlesnake’s age is often

a source of controversy. Many myths abound, including the myth that rattle-

snakes have no rattle at all for up to three years, or that they “throw off ” their

rattles. Th ey don’t, although they can break off . In truth, wild rattlesnakes

usually have fewer than 16 rattle segments, although snakes that are raised

in captivity may have more. Another misconception is that all species of the

rattlesnake can rattle. Some actually have rattles that make little to no noise.

4-6. More than half of snakebites occur with children

venomous snakebites in the mojave

all oth

ersr

attle snakes

env

eno

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76

Th e most notable characteristic of all rattlesnakes

found in the Mojave is the typical presence of the

rattle or string of rattles at the end of the tail. Th e

lightweight, hollow rattle string is composed of

interlocking rattle segments with multiple lobes

on each segment of the rattle.

or pets.

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79

rept

ile

4-7. This scatter chart compares the two components of speed and range of the strike that the typical

rattlesnake will have. This data compares well with the

overall strike range of mojave snakes

snakes in the Mojave region.

A rattlesnake’s fangs function like hypodermic needles to deliver venom.

Th ese long, thin, hollow specialized front teeth fold up and lie fl at against the

roof of the mouth when not in use. Within the gum, the base of each fang is

connected to the venom apparatus that lies further back in the mouth. Fangs

are frequently broken off or shed, and new fangs replace the lost ones within

a few weeks. Th e fangs are extended to about 90 degrees only to inject venom;

otherwise, they are retracted and are not used when swallowing prey.

There is often confusion regarding the terms bite and strike. To make a bite

a rattlesnake must only open its mouth and embed its fangs. A more restrained

rattlesnake can bite (as can a decapitated rattlesnake head), but it can’t

strike because that involves coordinated movement of the head, neck, and

body of the whole snake.

Unrestrained rattlesnakes typically deliver a bite via a strike; defi ned as the

rapid movement of the head towards a target, carried out by extension of

the head and front part of the snake body, with the middle and tail end

(posterior) of the body remaining stationary. While a rattlesnake can bite

from a fully extended or uncoiled body position, the strike is almost always

delivered to the victim from

a striking coil.

env

eno

m

78

20

0

10

spe

ed

(m

/s)

10 05

10 15 25

20

range (feet)

Page 41: Envenom; poisonous desert animals

81

rept

ile

Symptoms generally occur immediately, but only about one third of all bites

manifest symptoms. When no symptoms occur, probably little to no venom

was injected into the victim. In 50 percent of Mojave snake bites, very little

venom is injected because the snake has to chew the skin for envenomation

to occur. In as many as 25 percent of all venomous pit viper bites, no venom

is injected, possibly because the fangs may be injured, the venom sacs may

be empty at the time of the bite, or the snake may not use the fangs when it

strikes. Poisonous snakebite venom contains some of the most complex toxins

known; venoms can aff ect the central nervous system brain, heart, kidneys, and blood.

4-8. This timetable shows how long a snakebite victim has

before the bite becomes life threatening and the prey

effects of a venomous snakebite

has to survive the envenomation.

env

eno

m

80

The clinical effects of envenomation include

pain, swelling, and tenderness at the site, steady

increased swelling and bruising away from the

bite site. Low blood pressure and dizziness with

uncontrollable nausea along with some vomit-

ing and diarrhea. Numbness ocurring especially

around the mouth, muscle twitching, diffi culty

breathing, confusion, and ultimately uncon-

sciousness. Frequently, the limb that has been

envenomated will swell tremendously and will

become purple from blood that has leaked out

of blood vessels. Blood blisters may also form

around the area of the bite.p

ain

swe

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40

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Th e venom of diff erent

species also varies what the

overall eff ect of a snakebite

will be. Some venom acts

directly on the nervous

system while others may

simply apply toxicity

solely in local tissues.

Page 42: Envenom; poisonous desert animals

83

rept

ileenv

eno

m

82

Rattlesnakes and other crotalids use their venom primarily to fi rst halt the

victim, then kill, and digest prey, and as a certain defense against predators

and aggressors. Th is becomes the primary mechanism of an envenomous

toxicity is blood system massive leakage of blood vessels, causing danger-

ous cardiovascular shock from a loss of fl uid directly within the vascular

system into the surrounding cells and tissues. Th e venom interferes with

the typical normal blood clotting mechanism, thereby quickly increasing

the rate of internal bleeding. Th e components of some kinds of crotaline

venoms, especially Mojave toxin also cause neuromuscular paralysis, which

can result in a speedy death from respiratory arrest.

Lacking external ear openings, hearing in snakes senses vibrations. Th eir eye-

sight is basically poor, sensitive only to movement. Snakes usually fi nd prey

with their advanced sense of smell. Snakes have a specialized organ called

the Jacobson’s Organ, which consists of two pits lined with a sensory tissue.

When snakes fl ick their tongue, tiny particles of scent are transported to the pits behind the venom gland.

Snake size inf luences venom delivery. Bigger

rattlesnakes really do inject more venom. More

recently, we have begun to examine defensive

strikes, which are particularly important to the

problem of human snakebite. Rattlesnakes also

appear to inject more venom into study models

of human limbs (warm, human-scented, saline

fi lled gloves) than into mice. However, roughly

10 percent of the bites are dry, which is much

more frequent than that observed for predatory

bites. Large rattlesnakes inject far more venom

than small rattlesnakes when biting defensively.

Th e larger rattlesnakes have much more venom

available and experimental evidence from preda-

tory strikes suggests that even smaller snakes can

control, or meter, their venom

according to their sense of prey.

del

iver

ing

sn

ake

ven

om

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85

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eno

m

84

4-9. These data were obtained from the predatory strikes of various-sized Rattlesnakes (Crotalus

viridis). Even though baby and juvenile rattlesnakes have more toxic venom larger snakes have

substantially more

predatory strikes of rattlesnakes

venom in the glands and they use it.

Venom is ejected from the fangs, sometimes in multiple pulses which is most

commonly observed when a snake is physically restrained and sometimes

even from a third or reserve fang. Venom extraction which is commonly

called “venom milking,” is a very dangerous practice and conducted with

research professionals and only for legitimate reasons. It is actually true that

most professionals who extract venom eventually suff er a serious or even

fatal snakebite. Extractions should be performed only to study venom or the

mechanics of venom expulsion. Th e fl ow of venom is controlled by the snake.

rept

ile20

0

0

ve

no

m e

xp

en

de

d (

mg

)

snout-vent length (cm)

10

20 30

40 60

50

Milking snakes can be quite important, as

venom is the key ingredient in anti-venom.

Or “antivenin” as it is often called. Th e Irula

people in Tamil Nadu, India, actually make

their living as snake milkers, who catch, milk

and release the wild snakes. Th ere are certain

anti-venoms can fetch 2,000 dollars per gram.

Venom procurement may off er econom

ic opportunities.

Several companies around the

world collect and breed snakes

to be used in producing their

venom. Th e practice is vital in

protecting snake species while

providing income for the more

traditional snake hunter. All

Mojave snakes, however, are

currently protected by law

against venom procurement.

Page 44: Envenom; poisonous desert animals

env

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86 87

total snake envenomations in the mojave desert

4-10. Overall snake envenomations in the United States has steadily decreased. In the Mojave much

of this decline is largely the result of the overall education about

While getting bitten by a snake might strike fear in people, the fangs are not

where the venom comes from, they are simply methods of transfer. Th e place

where the venom is made is in special glands located on the head of the ani-

mal. Th e venom glands diff erentiate into false and true venom glands.

False venom glands are made up either from mucus producing supralabial

glands that run on either side of the head extending as a continuous strip

from near the snout to below and well tucked behind the eye. Th ese then lead

to several ducts thatle

arn

ing

beh

avio

r

lead to the bases of the teeth

the overall behavior of envenomous anim

als. rept

ile10 ,000

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Snakes are not slimy but if they get frightened

they may defecate on you as a way of showing

fear. If this happens, be sure to wash the area

thoroughly with soap and hot water, as snakes do

carry salmonella bacteria in their feces. It is help-

ful to remember when you are holding a snake

that it likely sees you as a very odd tree, and does

not recognize you as a human being. Snakes also

react by instinct rather than thought, and as long

as you keep this in mind, being around snakes is

very easy to do as well as being interesting observation experience.

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88 89

Animals who do envenomate do so for survival.

Th ere are many ways to prevent envenomation.

Some bites, such as those bites infl icted when you

step on a snake are nearly impossible to prevent.

However, there are precautions that can reduce

your chances of being bitten by a snake. Th ese

include leaving snakes alone. More often people

are bitten because they try to kill a snake or get

too close to it. Stay out of any tall grass unless

you wear thick leather boots and remain on the

hiking paths as much as possible. Keep hands and

feet out of areas you cannot see. Do not pick up

rocks or fi rewood unless you are clearly out of

a snake’s striking distance. Be cautious and alert

when climbing rocks. If you are bitten, don’t use

any tourniquet, as this isolates the venom across

only a small area and causes the digestive enzymes

in the injected venom to concentrate the damage.

Don’t use alcohol orally as it speeds the heart and

blood fl ow and reduces the body’s counteracting ability.

rept

ile

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Ashton, Ray Jr. and Patricia Sawyer Ashton. Reptiles and Amphibians: Part One, Th e

Snakes. Miami. Windward. 1988.

Bauchot, Roland. Snakes: A Natural History. [translated from the French by Catherine

Berthier]. New York: Sterling. 1994.

Gotch, A.F. Reptiles, Th eir Latin Names Explained. New York: Blandford Press, 1986.

Hayes, 1995, Animal Behavior. 50:33–40; Hayes et. al., 1995.

Klauber, L.M. Rattlesnakes: Th eir Habitats, Life Histories, and Infl uence on Mankind. Second

Edition. First published in 1956, 1972. University of California Press, Berkeley. 1997.

Mattison, Chris. Lizards of the World. New York: Facts on File. 1989.

McGavin, George. Insects, Spiders, and Other Terrestrial Arthropods. London; New

York, N.Y. : Dorling Kindersley, 2002.

Mehrtens, John M. Living Snakes of the World. New York. Sterling Publishing Co. 1987.

Munro, P. et al. A Mojave Dictionary. Los Angeles: ucla, 1992.

Nevada’s Plants and Animals: Banded Gila Monster. (n.d.); Retrieved from http://

www.dfg.ca.gov/hcpb/species/jsp/

bibliog

raph

y

91

ind

exen

ven

om

90

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ind

ex

chapter one

1-1. page 13 average annual hospitilization for mojave animal bites

1-2. page 15 the mojave desert

1-3. page 17 overall venom use in the mojave desert

1-4. page 18 mojave prey

1-5. page 20 common dangerous and nondangerus mojave animals

1-6. page 23 clinical effects of envenomation

chapter two

2-1. page 33 major areas of venomous arthropod populations

2-2. page 37 clinical effects of envenomation from mojave arthropods

2-3. page 39 location of the chelicerae in the arthropods

2-4. page 40 dorsal view of the brown recluse spider

chapter three

3-1. page 55 bufo alvarius

3-2. page 57 clinical effects of desert toad poisoning

chapter four

4-1. page 65 major areas of gila monster habitats

4-2. page 67 the decline in groundwater and lizard populations

4-3. page 68 untreated gila monster envenomation

4-4. page 73 current estimated gila monster population

4-5. page 75 map showing location of lake mead area

4-6. page 76 annual venomous snakebites in the mojave

4-7. page 78 overall strike range of mojave snakes

4-8. page 80 effects of a venomous snake bite

4-9. page 84 predatory strikes of rattlesnakes

4-10. page 87 total snake envenomations in the mojave desert

ind

ex

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