Animals can be traced to a common ancestor a …Animals can be traced to a common ancestor a...

Animals can be traced to a common

ancestor a flagellated protist like a

choanoflagellate (700 MYA)

Reproductive

cells

Somatic

cells

Digestive

cavity

1 Colonial protist,

an aggregate

of identical cells

2 Hollow sphere

of unspecialized

cells (shown in

cross section)

3 Beginning of cell

specialization

(cross section)

4 Infolding

(cross section)

5 Gastrula-like

“proto-animal”

(cross section)

The ancestor of animals was probably a colonial,

flagellated protist

– Cells in these protists

• Gradually became more specialized and layered

Figure 18.2A

Invertebrate: Porifera Sponges

– no distinct tissues or organs

• do have specialized cells

– no symmetry

– sessile (as adults)

food taken into each

cell by endocytosis

Sponges have a relatively simple, porous body

– Sponges, phylum Porifera

• Are the simplest animals and have no true tissues

INVERTEBRATES

Pores

Amoebocyte

Skeletal

fiber

Central

cavity

Choanocyte

in contact

with an

amoebocyte

Choanocyte

Water

flow

Flagella

– Flagellated choanocytes

• Filter food from the water passing through the porous

body

Invertebrate: Cnidaria Jellyfish, hydra, sea anemone, coral

– tissues, but no organs

– two cell layers

– radial symmetry

– predators

• tentacles surround

gut opening

• extracellular

digestion

– release enzymes

into gut cavity

hydra

stinging cell with nematocyst

trigger

discharged nematocyst

undischarged nematocyst

tentacles

mouth

sensory cell

stinging cell

Stinging cells of

Cnidarians

Cnidarians are radial animals with tentacles and

stinging cells

– Cnidarians, phylum Cnidaria

• Have true tissues and radial symmetry

– Their two body forms are

• Polyps, such as hydra

• Medusae, the jellies

Figure 18.6A–C

– They have a gastrovascular cavity

• And cnidocytes on tentacles that sting prey

Tentacle

“Trigger”

Coiled

thread

Capsule

(nematocyst)

Discharge

of thread

Cnidocyte Prey

Sea Nettle Portuguese man’o’ war

Sea wasp (box jelly)

Safe Comb Jellies

Invertebrate: Platyhelminthes

ectoderm

mesoderm

endoderm

Flatworms – tapeworm, planaria

– mostly parasitic

– bilaterally symmetrical

• allows high level of specialization

within parts of the body

• now have a mouth at one end

& an anus at the other!

Units with

reproductive

structures

Scolex

(anterior

end) Hooks

Sucker

Co

lori

zed

SE

M 8

0

Invertebrate: Nematoda

Roundworms

– bilaterally symmetrical

– have both mouth & anus

• well-developed digestive system

– many are parasitic

• hookworm

C. elegans

Ascaris

Invertebrate: Mollusca

Mollusks

– clams, snails, squid

– bilaterally symmetrical (with exceptions)

– soft bodies, mostly protected by hard shells

– true coelem

Gastropods

– Gastropods are the largest group of molluscs

• And include the snails and slugs

Bivalves

– The bivalves have shells divided into two halves

• And include clams, oysters, mussels, and scallops

Cephalopods

– Cephalopods are adapted to be agile predators

• And include squids and octopuses

Wiwaxia – between mollusca and annelida

Open Versus Closed

circulatory System

Open circulatory system – A heart pumps

hemolymph through a hollow cavity to circulate

O2 and nutrients.

Arthropods and some molluscs

Closed Circulatory System – a Heart pumps blood

through”closed” blood vessels and lymph is kept

separate.

Chordates, cephalopods and annelids

Invertebrate: Annelida – Segmented worms

• earthworms, leeches

• segments are not specialized

• bilaterally symmetrical

• true coelem

fan worm leech

Invertebrate: Arthropoda

Spiders, insects, crustaceans

– most successful animal phylum

– bilaterally symmetrical

– segmented

• allows jointed appendages

– exoskeleton

• chitin + protein

Arthropod groups

insects 6 legs, 3 body parts

crustaceans gills, 2 pairs antennae

crab, lobster, barnacles, shrmp

arachnids 8 legs, 2 body parts

spiders, ticks, scorpions

Chelicerates

– Chelicerates include

• Horseshoe crabs

• Arachnids, such as spiders, scorpions, mites, and ticks

A scorpion (about 8 cm long)

A black widow spider (about

1 cm wide)

A dust mite (about 420

µm long)

Colo

rize

d S

EM

90

0

Figure 18.11B, C

Millipedes and Centipedes

– Millipedes and centipedes

• Are identified by the number of jointed legs per body

segment

Crustaceans

– The crustaceans

• Are nearly all aquatic

• Include crabs, shrimps, and barnacles

Insects are the most diverse group of organisms

– Insects have a three-par t body consisting of

• Head, thorax, and abdomen

• Three sets of legs

• Wings (most, but not all insects)

– Many insects undergo

• Incomplete or complete metamorphosis

A. Order Or thoptera

– The order orthoptera includes

• Grasshoppers, crickets, katydids, and locusts

Head Thorax Abdomen

Antenna Forewing

Eye

Mouthparts Hindwing Figure 18.12A

B. Order Odonata

– The order odonata includes

• Dragonflies and damselflies

Figure 18.12B

C. Order Hemiptera

– The order hemiptera includes

• Bedbugs, plant bugs, stinkbugs, and water striders

Figure 18.12C

D. Order Coleoptera

– The order coleoptera includes

• Beetles

Figure 18.12D

E. Order Lepidoptera

– The order lepidoptera includes

• Moths and butter flies

Figure 18.12E

F. Order Diptera

– The order Diptera includes

• Flies, fruit flies, houseflies, gnats, and mosquitoes

Haltere

Figure 18.12F

G. Order Hymenoptera

– The order hymenoptera includes

• Ants, bees, and wasps

Figure 18.12G

Chapters 32- 34

The Animal Kingdom

Domain Eukarya

– Kingdom Animal

• Clade Deuterostome

• Phylum – Echinodermata

• Phylum - Chordata

Echinoderms have spiny skin, an endoskeleton,

and a water vascular system for movement

– Echinoderms, phylum Echinodermata

• Includes organisms such as sea stars and sea urchins

• Are radially symmetrical as adults

Tube foot

Tube foot

Spine

Figure 18.13B, C

– The water vascular system

• Has suction cup–like tube feet used for respiration and

locomotion

Anus

Spines

Tube feet

Canals

Stomach

Figure 18.13A

Invertebrate: Echinodermata Starfish, sea urchins, sea cucumber

– radially symmetrical

– spiny exoskeleton

The body plans of animals can be used to build

phylogenetic trees

– One hypothesis of animal phylogeny

• Is based on morphological comparisons

Ancestral

colonial protist

No true tissues True tissues

Bilateral symmetry Radial symmetry

Eumetazoans

Bilaterians

Protostomes Deuterostomes

Spo

nges

Cnid

aria

ns

Ech

ino

der

ms

Cho

rdat

es

Fla

two

rms

Mo

llusc

s

Annel

ids

Art

hro

po

ds

Nem

ato

des

Deuterostome Clade

Echinoderms (seastars and sea urchins) and

Chordates (Us) are monophyletic.

Protostomes make up two clades:

Lophotrochozoa and Ecdysozoa.

Lophotrochozoa are split into 2 groups:

Trochopore larva (annelida and mollusca)

and Lophophore bearing (flatworms, rotifers).

Ecdysozoans shed an old exoskeletons

(Nematodes and Arthropods).

Our own phylum, Chordata, is distinguished by

four features

– Chordates, phylum Chordata have

• A dorsal hollow ner ve cord

• A stiff notochord

• Pharyngeal slits

• A muscular post-anal tail

Vertebrate Evolution and

Diversity

Campbell’s Chapter 34

Vertebrates belong to Phylum

Chordata

Chordata also includes:

– Urochordates - Tunicates

– Cephalochordates - Lancelets

Vertebrates

– fish, amphibians, reptiles, birds, mammals

– internal bony skeleton

• backbone encasing

spinal column

• skull-encased brain

postanal tail notochord

hollow dorsal nerve cord

pharyngeal pouches

Chordata

becomes brain & spinal cord

becomes vertebrae

becomes gills or Eustachian tube

becomes tail or tailbone

Oh, look… your first baby picture!

All Chordates possess 1. Notochord - A rigid but flexible rod

between the digestive tube and the

dorsal nerve cord.

2. Dorsal hollow Nerve cord

3. Pharyngeal Slits

4. Muscular, Post-anal Tail

Chordate Characteristics

Subphylum

Urochordates –

tunicates - seasquirts

Cephaloch

ordate -

Lancelets

Transitional Species – 530 mya

Haikouichthys – A true vertebrate

Myllokunmingia - early vertebrate

Neural crest Forms from closing neural tube and will form

parts of the bones and cartilage of the cranium.

Agnathans – Jawless

Ostracoderms – 450-375 million years ago

Hagfish – slime-eels

Has a cranium but no jaws, teeth or

backbone.

Still has Notochord

Sea Lampreys

Have a cranium and a cartilaginous partial

wrapping around notochord.

No jaws or teeth.

Jaws evolved from Pharyngeal

slits supports.

Vertebrates: Fish salmon, trout, sharks

450 mya

Characteristics

– body structure

• bony & cartilaginous skeleton

• jaws & paired appendages (fins)

• scales

– body function

• gills for gas exchange

• two-chambered heart;

single loop blood circulation

• ectotherms

– reproduction

• external fertilization

• external development in

aquatic egg

gills

body

Chondrichthyes – includes

Sharks and rays Jawed fish with Catilaginous skeletons

Have teeth and a lateral line

Sharks have been around for more than 400

million years.

Sharks existed about 200 million years

before dinosaurs.

There are more than 375 species of sharks

living today.

Megalodon

Fake

Whale Shark – Largest extant

fish 30 – 40 feet

Osteichthyes – Bony fish have

Calcified endoskeleton

Operculum – gill covering

30,000 species

Water comes in mouth through pharynx and

out through the gills

Swim bladder is used for buoyancy and

came from lungs

Osteichthyes – Bony fish

Three Extant groups (classes)

– Actinopterygii – ray finned fish

– Actinista – Lobed finned fish

– Dipnoi - Lungfish

Actinopterygii – ray finned fish

Include commonly known fish like trout, perch and

flounder.

1. Skin secrete mucus that reduces drag

2. Have keratin scales

3. Most reproduce externally

4. Two Chambered heart

5. Ectothermic

Anatomy of typical Ray finned

fish

Actinista – Lobed finned fish

Walk on bottom with muscular fins

Coelacanth

Dipnoi - Lungfish

All living lungfish live in

the remnants of

Gondwana; Australia,

Africa and South America

Have an amphibian-like lung

Tetrapod evolution from fish

The split between fish and amphibians is

very blurry.

Lungfish and frogs breath the same way

Fossil

record

From fish to Amphibians

Tiktaalik

Fish with a

neck

Tibia

Femur

Fibula

Humerus Shoulder

Radius Ulna

Tibia

Femur Pelvis

Fibula Lobe-finned fish

Humerus

Shoulder

Radius

Ulna

Pelvis

Early amphibian

Acanthostega – tetrapod FISH

Ichthyostega

Class - Amphibians

Amphi (two) bios (lives) – spend part of

the time in water and part on land

1. Breath through lungs and moist skin

2. Eggs are laid in water and larva (tadpoles)

lose lateral line.

3. Ectothermic

4. Three Chambered heart

lung

buccal cavity

glottis closed

Vertebrates: Amphibian Amphi (two) bios (lives) – spend part of the time in

water and part on land

Characteristics

– body structure

• legs (tetrapods)

• moist skin

– body function

• lungs (positive pressure) & diffusion through skin for gas exchange

• three-chambered heart; veins from lungs back to heart

• ectotherms

– reproduction

• external fertilization

• external development in aquatic egg

• metamorphosis (tadpole to adult)

frogs

salamanders

toads

350 mya

Orders

– Order Urodela – (tailed ones) Salamanders

– Order Anura – No tails – frogs and toads

– Order Apoda – no legs – legless

Urodela

500 species

Lungless

Anurans

4,200 species

Lungless frog

Apodans

150 species

The Amniotes

Class – Mammals - you

Class – Testudines - turtles

Class – Sphenodontia - tuataras

Class – Squamata – snakes and lizards

Class – Crocodilia- crocodiles and alligators

Class – Aves - birds

Amniotic Egg

The egg has a shell that allows the animal to live

on land exclusively (although many have returned

to the water).

Extraembryonic membranes

– Allantois – disposal of waste

– Amnion – protects embryo and prevents

dehydration

– Chorion – Exhange gases for the embryo

– Yolk Sac – contains nutrients in yolk

Skull features separated the

Earliest Amniotes

Synapsids - (One opening behind temple)lead to

therapsids and mammals

Anapsids - (No openings on the temple of the skull)lead to

An extinct group of reptiles (and maybe turtles)

Diapsids – (two arches opening) Lead to the dinosaurs,

modern reptile, archesaurs and birds

Dimetrodon – a mammal-like reptile

Titanophoneus a dominant

Therapsid

Reptilian Heritage evident

Terrestrial adaptations:

– Keratin scales protect from dessication (drying out)

– Must get all air from their lungs.

– Fertilization is internal

– Ectothermic –absorb external heat but have behaviors that assist in temperature control.

– Three chambered heart

– The first radiation was based upon skull differences and happened about 250 MYA

Vertebrates: Reptiles Characteristics

– body structure

• dry skin, scales, armor

– body function

• lungs for gas exchange

• thoracic breathing; negative pressure

• three-chambered heart

• ectotherms

– reproduction

• internal fertilization

• external development in amniotic egg

250 mya dinosaurs, turtles

lizards, snakes

alligators, crocodile

embryo leathery shell

chorion

allantois yolk sac

amnion

The age of Reptiles

The Mesozoic Era saw a wide diversification of reptiles and their cousins the dinosaurs.

From 251 to 65 MYA

When the dominant amphibians and therapsids went extinct at the end of the Permian (also ending the Paleozoic Era) Dinosaurs took over.

Testudines Turtles – no openings in temples but other

factors do not link them to the other

anapsids.

Newly discovered fossil from China has shed light on how the turtle's shell

evolved.

The 220 million-year-old find, described in Nature journal, shows that the turtle's

breast plate developed earlier than the rest of its shell.

The breast plate of this fossil was an extension of its ribs, but only hardened skin

covered its back.

Diapsids split into

Lepidosauria – Extinct oceanic reptiles

– Sphenodontia

– Mosasaurs

– Plesiosaurs

– Ichthyosaurs

– Squamata – snakes and reptiles

Archosauria-

– Crocodilians

– Pterosaurs

– Ornithischia

– Saurischians

– Aves

Leptidosaurians

Class – Sphenodontia - tuataras

Last of a primitive reptile found only in

New Zealand

Archosauria

– Crocodilians

– Pterosaurs

– Ornithischia

– Saurischians

– Aves

Crocodilians

Alligators and Crocodiles

pterosaurs

Ornithschians – Herbivorous and extinct

Saurishians – Herbivorous and carnivorous

She’s a he!

Archaeopteryx

Vertebrates: Birds

Characteristics

– body structure

• feathers & wings

• thin, hollow bone; flight skeleton

– body function

• very efficient lungs & air sacs

• four-chambered heart

• endotherms

– reproduction

• internal fertilization

• external development in amniotic egg

150 mya finches, hawk

ostrich, turkey

trachea

anterior air sacs

lung

posterior air sacs

Birds are a branch of the

Saurischians

Birds

8,600 species

Ratite birds are flightless.

Form and function

Four chambered heart

Endothermic

Hatched from eggs

Vertebrates: Mammals Characteristics

– body structure

• hair

• specialized teeth

– body function

• lungs, diaphragm; negative pressure

• four-chambered heart

• endotherms

– reproduction

• internal fertilization

• internal development in uterus

– nourishment through placenta

• birth live young

• mammary glands make milk

(specialized sweat glands)

220 mya / 65 mya mice, ferret

elephants, bats

whales, humans

muscles contract

diaphragm contracts

Split into three groups from the

therapsids during the Mesozoic

The Monotremes – egg

layers

Marsupials – pouches

Eutherians – Placental

mammals

Marsupials versus Eutherians

Probably split ~125 MYA

Marsupials radiated in the southern

continents

Eutherians radiated in the northern land

masses and spread south.

A great deal of Convergent Evolution

Vertebrates: Mammals

Sub-groups

– monotremes

• egg-laying mammals

• duckbilled platypus, echidna

– marsupials

• pouched mammals

• short-lived placenta

• koala, kangaroo, opossum

– placental

• true placenta

• shrews, bats, whales, humans

Whale ancestor

Vertebrate quick check… Which vertebrates lay eggs with shells?

Which vertebrates are covered with scales?

What adaptations do birds have for flying?

What kind of symmetry do all vertebrates have?

Which vertebrates are ectothermic and which are

endothermic

Why must amphibians live near water?

What reproductive adaptations made mammals very

successful?

What characteristics distinguish the 3 sub-groups of

mammals?

2007-2008

That’s

the buzz!

Any

Questions?