Envenom; poisonous desert animals
description
Transcript of Envenom; poisonous desert animals
ENVENOc
om
piled by m
. hill
ven
om
ou
s and
poiso
no
us an
imals
of th
e mo
jave d
esert
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
boo
k desig
n © 20
09 by m
. hill
bind
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, oak
land
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CONTENTsix 1 1 3 1 5 1 6 3 90 93
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
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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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.
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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lifor
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vad
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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
itat
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at an invader.
of symbiosis.
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
end
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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
rou
tin
g
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.
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
ar
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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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fig
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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.
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
hab
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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
ar
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through their cuticles.
the scorpions.
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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arth
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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.
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
ropo
d
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
eno
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38
for Mojave plant life.
co
nn
ecti
ng
pai
rs
hind pincers.
ar
th
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d
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
env
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40
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.
env
eno
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42
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
ar
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ropo
d
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
.
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
env
eno
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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.
ar
th
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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.
ar
th
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d
49
env
eno
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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
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
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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eno
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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
am
phibia
n
55
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eno
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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.
am
phibia
n
57
env
eno
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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)
am
phibia
n
59
env
eno
m
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.
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
am
phibia
n
61
env
eno
m
60
it plays with sunlight.
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.
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.
20
-20
0
gr
ou
nd
wa
ter
we
ll t
est
le
ve
ls (
inc
he
s)
198
0
198
5
199
0
199
5
20
05
20
00
year
67
env
eno
m
66
rept
ile
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.
69
env
eno
m
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
swe
llin
g
vo
mit
ing
nu
mb
ne
ss
ne
cr
osi
s
he
ad
ac
he
blu
rr
ed
vis
ion
re
spir
ato
ry
ar
re
st
de
ler
iou
s
co
nv
uls
ion
s
de
ath
24
0
12
tim
e (
ho
ur
s)
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
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
m
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.
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
e me
ad
ca
lifor
nia
co
lor
ad
o r
ive
r
ar
izon
ia
vir
gin
riv
er
ne
vad
a
env
eno
m
74
snak
es
dangerous and venomous.
in this region.
100
0
50
ve
no
mo
us
bit
es
(pe
rc
en
t)
198
9
199
9
20
09
197
9
year
77
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
m
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.
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)
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
llin
g
vo
mit
ing
nu
mb
ne
ss
ne
cr
osi
s
he
ad
ac
he
blu
rr
ed
vis
ion
re
spir
ato
ry
ar
re
st
de
ler
iou
s
co
nv
uls
ion
s
co
ma
de
ath
40
0
50
tim
e (
ho
ur
s)
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.
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
85
env
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.
env
eno
m
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
0
5,000
sna
ke
en
ve
no
ma
tio
ns
198
0
198
5
199
0
199
5
20
05
20
00
year
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.
env
eno
m
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
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
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exen
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om
90
env
eno
m
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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