UNDERSTANDINGS:•The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses.•When species are discovered they are given scientific names using the binomial system.•Taxonomists classify species using a hierarchy of taxa.•All organisms are classified into three domains.•The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species.•In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one common ancestral species.•Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species.•Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group.

TOPIC 5.3 CLASSIFICATION OF BIODIVERSITYESSENTIAL IDEA: SPECIES ARE NAMED AND CLASSIFIED USING AN INTERNATIONALLY AGREED SYSTEM

Applications and skills:•Application: Classification of one plant and one animal species from domain to species level.•Application: Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta.•Application: Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda and chordata.•Application: Recognition of features of birds, mammals, amphibians, reptiles and fish.•Skill: Construction of dichotomous keys for use in identifying specimens.

TOPIC 5.3 CLASSIFICATION OF BIODIVERSITYESSENTIAL IDEA: SPECIES ARE NAMED AND CLASSIFIED USING AN INTERNATIONALLY AGREED SYSTEM

CLASSIFICATION OF INVERTEBRATE ANIMALSTopic 5.3

PLANTAE“PROTISTS” ANIMALIAFUNGI

Ap

ico

mp

lexa

ns

Cili

ates

Kin

eto

pla

stid

s

Eu

gle

nid

s

Dip

lom

on

ads

Ph

aeo

ph

yta

(bro

wn

alg

ae)

Oo

myc

ota

(wat

er m

old

s)

Rh

od

op

hyt

a(r

ed a

lgae

)

Ch

loro

ph

yta

(gre

en a

lgae

)

Bry

op

hyt

a(l

iver

wo

rts,

mo

sses

)

Pte

rid

op

hyt

a(f

ern

s)

Zyg

om

yco

ta

Am

oeb

ozo

ans

Asc

om

yco

ta

Bas

idio

myc

ota

Po

rife

ra(s

po

ng

es)

Cn

idar

ia(a

nem

on

es, j

elly

fish

)

Pro

tost

om

es(w

orm

s, a

rth

rop

od

s, m

ollu

sks)

Deu

tero

sto

mes

(sea

urc

hin

s, s

ea s

tars

, ver

teb

rate

s)

Dia

tom

s

Din

ofl

agel

late

s

An

gio

sper

ms

(flo

wer

ing

pla

nts

)

Gym

no

sper

ms

EUKARYOTIC TREE OF LIFE

WHAT ARE THE KEY FEATURES OF ANIMALS?

Animals possess all of the following characteristics Multicellularity Their cells lack a cell wall They obtain energy by consuming other

organisms Most reproduce sexually They are motile at some point in the life cycle They are able to respond rapidly to external

stimuli

AN EVOLUTIONARY TREE OF SOME MAJOR ANIMAL PHYLA

LACK OF TISSUES SEPARATES SPONGES FROM ALL OTHER ANIMALS

Tissues are groups of similar cells that carry out a specific function (e.g., muscle)

Sponges are the only modern-day animals that lack tissues Individual cells in sponges may be specialized, but they act independently and are not organized into true tissues

Sponges and all remaining tissue-containing phyla arose from an ancient common ancestor without tissues

PORIFERA (SPONGES) Sponges have a simple body plan found in most marine and aquatic

environments occur in a variety of sizes and shapes may reproduce asexually by budding or

sexually through fusion of sperm and eggs

CNIDARIANS

Sea jellies, sea anemones, corals, and hydrozoans belong to the phylum Cnidaria

These animals are mostly marine and are all carnivorous predators

The cells of cnidarians are arranged into distinct tissues, including a contractile muscle-like tissue and an organized nerve net

PLATYHELMINTHES (FLATWORMS) may be parasitic or free living in aquatic,

marine, and moist terrestrial habitats are bilaterally symmetrical can reproduce both sexually and asexually;

most are hermaphroditic, having both male and female sexual organs

head (attachment site)adult tapeworm

7

5

6

1

2

3

4

8

6 inches

A larvaltapewormis liberated bydigestion and attaches tothe human’sintestine

The tapeworm matures in a humanintestine, producing a series ofreproductive segments; each segmentcontains both male and female sex organs

Eggs are shed fromthe posterior end of theworm and are passedwith human feces

A pig eats foodcontaminated byinfected feces

Larvae hatchin the pig’s intestine

The larvae migrate throughblood vessels to pig muscle

The larvae formcysts in pig muscle

A human eatspoorly cookedpork withlive cysts

THE LIFE CYCLE OF THE HUMAN PORK TAPEWORM

Fig. 23-10

PLATYHELMINTHES (FLATWORMS)

Another group of parasitic flatworms is the flukes

Flukes have complex life cycles that include an intermediate host, such as a snail

Blood flukes cause schistosomiasis, which causes symptoms such as diarrhea, anemia, and possible brain damage

As many as 200 million people worldwide may be infected with flukes

ANNELIDA (SEGMENTED WORMS) The annelid body is divided into a series of

repeating units (segmentation) The segments contain identical copies of nerves,

excretory structures, and muscles that allows for complex movement

Annelids have a fluid-filled coelom The coelom functions as a hydrostatic skeleton,

where pressurized fluid provides a framework against which muscles can act

One way digestive tract

MOLLUSCA The three classes of mollusks are:

Gastropods Bivalves Cephalopods

MOLLUSCA - GASTROPODS are one-footed crawlers

The snails and slugs are collectively known as gastropods They have a muscular foot for locomotion They may possess a shell, but not all gastropods are

shelled They feed using a radula, a flexible ribbon studded

with spines that scrape algae from rocks or grasp larger plants or prey

Most use their skin and gills for respiration, but terrestrial mollusks have a simple lung

MOLLUSCA - BIVALVES are filter feeders

Bivalves include scallops, oysters, mussels, and clams They live in fresh water and marine habitats They possess two shells that can be clamped shut by a

strong muscle They are filter feeders and use gills for both feeding

and respiration Most have a muscular foot used for burrowing or for

attaching to rocks

MOLLUSCA - CEPHALOPODS are marine predators

Cephalopods have tentacles with chemosensory abilities and suction disks

These animals are able to move rapidly by forcefully expelling water from the mantle cavity

They possess closed circulatory systems

ARTHROPODS

Arthropods are the most diverse and abundant animals The phylum Arthropoda includes insects,

arachnids, myriopods, and crustaceans Arthropods have appendages and an

exoskeleton (external skeleton) The exoskeleton is secreted by the epidermis (the

outer layer of skin) It is composed primarily of protein and chitin (a

polysaccharide)

THE EXOSKELETON MUST BE MOLTED

Fig. 23-18

THE DIVERSITY OF ARACHNIDS

Fig. 23-22

THE DIVERSITY OF MYRIAPODS

Fig. 23-23

THE DIVERSITY OF CRUSTACEANS

Fig. 23-24

ECHINODERMS calcium carbonate

skeleton includes sand dollars, sea

urchins, sea stars, sea cucumbers, and sea lilies Echinoderm larvae exhibit

bilateral symmetry; adults show radial symmetry

They exhibit deuterostome development

They possess an endoskeleton (internal skeleton) that sends projections through the skin

PHYLUM CHORDATA

The phylum Chordata includes two invertebrate groups (the sea squirts and the lancelets) plus the vertebrates

CLASSIFICATION OF VERTEBRATE ANIMALS

Applications and skills:•Application: Classification of one plant and one animal species from domain to species level.•Application: Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta.•Application: Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda and chordata.•Application: Recognition of features of birds, mammals, amphibians, reptiles and fish.•Skill: Construction of dichotomous keys for use in identifying specimens.

TOPIC 5.3 CLASSIFICATION OF BIODIVERSITYESSENTIAL IDEA: SPECIES ARE NAMED AND CLASSIFIED USING AN INTERNATIONALLY AGREED SYSTEM

Vertebrates

TetrapodsC

ho

nd

rich

thye

s(s

har

ks,

rays

)

Act

inis

tia

(co

elac

anth

s)

Act

ino

pte

ryg

ii(r

ay-f

inn

ed f

ish

)

Pet

rom

yzo

nti

form

es(l

amp

reys

)

Dip

no

i(l

un

gfi

shes

)

Am

ph

ibia

(fro

gs,

sala

man

der

s)

Rep

tili

a(t

urt

les,

sn

akes

cro

cod

iles

,b

ird

s)

Mam

mal

ia(m

amm

als)

Dorsal nerve cord, notochord,pharyngeal gill slits, post-anal tail

Vertebral column

Jaws

Lungs

Skull

Lobed fins

Limbs

Amniotic egg

Hair, milk

AN EVOLUTIONARY TREE OF THE VERTEBRATES

VERTEBRATE ADAPTATIONS Several adaptations have allowed vertebrates to

successfully invade most habitats presence of an internal skeleton that can grow and repair

itself allowed for greater size and mobility, enabling these animals to invade most habitats

Jaws evolved to allow these animals to exploit a much wider range of food sources than jawless animals that preceded them

The development of paired appendages (fins, legs, wings) helped to stabilize movement

The increased size and complexity of the brain and sensory structures allowed these animals to perceive their environment in detail and to respond in a variety of ways

WHAT ARE THE MAJOR GROUPS OF VERTEBRATES?

Today, vertebrates include the following groups: Lampreys Cartilaginous fishes Ray-finned fishes Lungfishes Amphibians Reptiles (and birds) Mammals

LAMPREYS Some

lampreys parasitize fish

jawless rounded

sucker that surrounds the mouth

spinal cord is protected by cartilaginous segments

live in both fresh and salt waters

CARTILAGINOUS FISHES Cartilaginous fishes are

marine predators They are of the class

Chondrichthyes, and include sharks, skates, and rays

Most are marine They possess jaws and

a cartilaginous skeleton Their body is protected

by a leathery skin embedded with tiny scales

BONY FISHES

the most diverse vertebrates Bony fish are found in nearly every watery

habitat, both freshwater and marine This group includes:

Ray-finned fishes, such as the angler fish, the moray eel, and the sea horse

Lobe-finned fishes, which include the lungfish and the coelacanth

THE DIVERSITY OF RAY-FINNED FISHES most diverse and abundant group of vertebrates

Fins which are formed by webs of skin supported by bony spines

bony skeleton skin is covered with interlocking scales two-chambered heart gills are for respiration Most have a swim bladder

LOBED-FINNED FISHES

fleshy fins that contain rod-shaped bones surrounded by a thick layer of muscle Some of these modified fleshy fins could be used to

drag the fish from a drying puddle to a deeper pool This gave rise to the first vertebrates to invade land—the

amphibians Some of the lineages of lobefins left descendents

that survive today and are the tetrapods (amphibians, reptiles, and mammals)

frogs, toads, salamanders, and caecilians

Amphibians begin life adapted to an aquatic environment (e.g., tadpoles have gills) They later mature into semi-terrestrial adults with lungs

three-chambered heart adults respire through lungs and

moist skin Most have four limbs Most are confined to moist habitats use of external fertilization requires

water eggs, protected only by a jelly-like

coating, are vulnerable to water loss

Amphibians:

REPTILES

class Reptilia and are adapted for life on land These animals evolved from an

amphibian ancestor about 250 million years ago Reptiles include lizards, snakes,

alligators, crocodiles, turtles, and birds They respire exclusively through lungs tough scaly skin that protects the body

and resists water loss internal fertilization with shelled

amniotic egg three- or four-chambered hearts efficient lungs and do not use their skin

as a respiratory organ

BIRDS

distinctive group of reptiles They appear in the fossil

record 150 million years ago

They are distinguished from other reptiles by feathers, which are highly specialized reptilian body scales

Modern birds retain scales on their legs, which is evidence of the ancestry they share with the rest of the reptiles The earliest known bird is

called Archaeopteryx

ARCHEOPTERYX, THE EARLIEST-KNOWN BIRD

MAMMALS

Mammals appeared in the fossil record about 250 million years ago They did not diversify and dominate terrestrial habitats until the

dinosaurs became extinct (65 million years ago) Mammals are warm-blooded with high metabolic rates a four-chambered heart hair that protects and insulates legs designed for running rather than crawling provide milk to their offspring sweat, scent, and sebaceous (oil-producing) glands, which

are not found in other vertebrates Mammals are subdivided into three groups

Monotremes Marsupials Placental mammals

are egg-laying mammals This group includes only three species, the platypus and

two species of spiny anteater (echidnas), and are found only in Australia and New Guinea Platypuses forage for food in the water and eat small vertebrate

and invertebrate animals Echidnas are terrestrial and eat insects and worms they dig out of

the ground Monotremes lay leathery eggs rather than giving birth to

live young The newly hatched young are nourished from milk secreted by

the mother

MONOTREMES

MARSUPIA Species include the opossums, koalas, kangaroos,

wallabies, wombats, and the Tasmania devil In marsupials, embryos begin development in the

uterus of the female Young are born at a very immature stage and must crawl

to and grasp a nipple to complete development Post-birth development, in most, is completed in a

protective pouch

PLACENTAL MAMMALS

inhabit land, air, and sea This highly diverse class

includes bats, moles, impalas, whales, seals, monkeys, and cheetahs The uterus contains a

placenta that functions in gas, nutrient, and waste exchange between circulatory systems of mother and embryo

In placental mammals, young are retained in the uterus for their entire embryonic development