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Animal Diversity I: Invertebrates

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Animal Key Features

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Anatomical Branch Points on the Animal Evolutionary Tree

• An evolutionary tree of some major animal phyla (F22.1 p. 424)

protostomesbilateral

deuterostomeslophotrochozoansecdysozoans

Porifera(sponges)

Cnidaria(jellyfish,corals,anemones)

Ctenophora(comb jellies)

Arthropoda(insects,arachnids,crustaceans)

Platyhelminthes(flatworms)

Annelida(segmentedworms)

Mollusca(clams,snails,octopods)

Echinodermata(sea stars,sea urchins)

Chordata(lancelets,vertebrates)

cuticle molted

protostome development deuterostome development

bilateral symmetryradial symmetry

no tissues tissues

Nematoda(roundworms)

Sponges: Lack Tissues

Radial or Bilateral Symmetry

Radial symmetry

central axisplane ofsymmetry

Bilateral symmetry

anteriorplane of symmetry

posterior

•Animals with Tissues Exhibit Either Radial or Bilateral Symmetry

Body symmetry and cephalization (F22.2 p. 425)

Anatomical Branch Points on the Animal Evolutionary Tree

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Anatomical Branch Points on the Animal Evolutionary Tree

–Embryonic Tissue Layers • Radially Symmetrical Animals Have Two• Bilaterally Symmetrical Animals Have Three

–Bilateral Animals Have Heads

– Most Bilateral Animals Have Body Cavities– Body Cavity Structure Varies Among Phyla

• Body cavities (F22.3 p. 426)

“True” coelom(annelids, chordates)

body wall

coelom

digestivetract

digestivecavity

}

}

“False” or pseudocoelom(roundworms)

body wall

pseudocoelom

digestivetract

digestivecavity

}

No coelom(cnidarians, flatworms)

body wall

digestivetractdigestive

cavity

}

Body cavities (F22.3 p. 426)

Anatomical Branch Points on the Animal Evolutionary Tree

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Anatomical Branch Points on the Animal Evolutionary Tree

• Simpler Body Cavities Evolved from Coelomate Body Plans

• Bilateral Organisms Develop in One of Two Ways– Protostomes Deuterostomes

• Protostomes: Two Distinct Evolutionary Lines– Ecdysozoans Lophotrochozoans

Comparison of the Major Animal Phyla (T22.1 p. 428)

epithelialcell

spicules

amoeboidcell

pore cell

collar cell

(water flow)

(water flow)

pore

osculum

Major Animal Phyla

Sponges: Simple Body Plan

(F22.4 p. 428)

Sponge diversity (F22.5 p. 429)

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• Cnidarians: Well-Armed Predators– Cnidarian diversity (F22.6 p. 430) – Polyp and medusa (F22.7 p. 431) – Cnidarian weaponry: the cnidocyte (F22.8

p. 431)

Major Animal Phyla

Major Animal Phyla

Cnidarians: Well-Armed Predators

Cnidarian diversity (F22.6

p. 430)

Polypmouth

lining ofgastrovascularcavity

tentaclegastrovascularcavity

column

foot

body wall

mesoglea

Medusa lining ofgastrovascularcavity

gastrovascularcavity

tentacle

mouth

mesoglea

body wall

Major Animal Phyla

Polyp and medusa (F22.7 p. 431)

nuclei

trigger

trigger

filament

Cnidarian weaponry:

the cnidocyte (F22.8 p. 431)

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Major Animal Phyla

• Flatworms – Organs – Lack Respiratory & Circulatory Systems– Flatworm organ systems (F22.9 p. 432) – The life cycle of the human pork tapeworm

(F22.10 p. 433)

nerve cord

excretorypore

brain

Excretorysystem

Nervoussystem

excretorycanal

Digestivesystem

eyespots

gastrovascularcavity

pharynx(with mouthat tip)

Major Animal Phyla

Flatworm organ systems

(F22.9 p. 432)

Major Animal Phyla

– Life cycle of human pork tapeworm (F22.10 p. 433)

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22.3 What Are the Major Animal Phyla?

• 22.3.4 Annelids Are Composed of Identical Segments– Figure 22.11 An annelid, the earthworm

(p. 434) – Figure 22.12 Diverse annelids (p. 435)

coelom

intestine

nephridia

excretory pore

ventralnerve cord

anus

coelom

brain

mouth

pharynxventralvessel

ventral nerve cord

hearts esophagus

crop gizzard intestine

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22.3 What Are the Major Animal Phyla?

• 22.3.5 Most Mollusks Have Shells– Figure 22.13 A generalized mollusk (p.

435) – 22.3.5.1 Gastropods Are One-Footed

Crawlers• Figure 22.14 The diversity of gastropod

mollusks (p. 436)

digestive tract

gonadheart

coelom

shell

mantle

anus

gill

nerve cords

foot

mouth

radula

eye

tentacle

ganglia(brain)

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22.3 What Are the Major Animal Phyla?

– 22.3.5.2 Bivalves Are Filter Feeders• Figure 22.15 The diversity of bivalve mollusks

(p. 436)

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22.3 What Are the Major Animal Phyla?

– 22.3.5.3 Cephalopods Are Marine Predators

• Figure 22.16 The diversity of cephalopod mollusks (p. 437)

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22.3 What Are the Major Animal Phyla?

• 22.3.6 Arthropods Are the Dominant Animals on Earth– Figure 22.17 The exoskeleton allows precise

movements (p. 438) – Figure 22.18 The exoskeleton must be molted

periodically (p. 438) – Figure 22.19 Segments are fused and specialized in

insects (p. 438) – Figure 22.20 Arthropods possess compound eyes

(p. 439)

abdomen

wing

thorax

head

antennae

compound eye

mouth parts

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22.3 What Are the Major Animal Phyla?

– 22.3.6.1 Insects Are the Only Flying Invertebrates

• Figure 22.21 The diversity of insects (p. 439)

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22.3 What Are the Major Animal Phyla?

– 22.3.6.2 Most Arachnids Are Predatory Meat Eaters

• Figure 22.22 The diversity of arachnids (p. 440)

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22.3 What Are the Major Animal Phyla?

– 22.3.6.3 Myriapods Have Many Legs• Figure 22.23 The diversity of myriapods

(p. 441)

(a) (b)

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22.3 What Are the Major Animal Phyla?

– 22.3.6.4 Most Crustaceans Are Aquatic• Figure 22.24 The diversity of crustaceans

(p. 441)

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22.3 What Are the Major Animal Phyla?

• 22.3.7 Roundworms Are Abundant and Mostly Tiny– Figure 22.25 A freshwater nematode (p.

442) – Figure 22.26 Some parasitic nematodes

(p. 443)

ovary

vagina

eggs

mouth

cuticle

posteriorend

anteriorend

intestine

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22.3 What Are the Major Animal Phyla?

• 22.3.8 Echinoderms Have a Calcium Carbonate Skeleton– Figure 22.27 The diversity of echinoderms

(p. 443) – Figure 22.28 The water-vascular system of

echinoderms (p. 444)

ampulla

tube feet

sieve plate

canalsplates ofendoskeleton

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22.3 What Are the Major Animal Phyla?

• 22.3.9 The Chordates Include the Vertebrates