Invertebrate Animals

(MOST Animals -- >95%!)

Animal Phylogeny

Invertebrates

PoriferaCnidariaPlatyhelminthesNematodaAnnelidaMolluscaArthropodaEchinodermata

Porifera (Sponges)• Simple, ALMOST Colonial

– No Symmetry– No Gut– 2 Tissue Layers– Acoelomate (“Spongocoel”)

• Sessile filter feeders

Porifera (Sponges)

Cnidaria (Jellyfish, Anemone)• Simple

– Radial Symmetry– Incomplete Gut = Gastrovascular Cavity

(GVC)– 2 tissue Layers– Acoelomate

• Sessile (Polyp) or Mobile (Medusa) forms

Cnidaria (Jellyfish, Anemone)

• Carnivores

• Tentacles with stinging cells– Cnidocytes

Cnidaria (Jellyfish, Anemone)

Platyhelminthes (Flatworms)• Simple

– Bilateral Symmetry– Incomplete Gut = Gastrovascular Cavity

(GVC)– 3 tissue Layers– Acoelomate– Protostomes

http://www.biology.ualberta.ca/courses.hp/zool250/Labs/Lab04/DugesiaCrawling.mov

• Incomplete GVC is finely branched.

• Simple Nervous System

• Simple Reproductive System

Platyhelminthes (Flatworms)

• Tapeworms

Platyhelminthes (Flatworms)

Nematoda (Smooth Roundworms)

• More Complex– Bilateral Symmetry– Complete Gut– 3 tissue Layers– Pseudocoelomate– Protostomes

• Many soil-dwellers

• Many parasites

• More complex Digestive System

• More complex Reproductive System

• No Circulatory system

Nematoda (Smooth Roundworms)

Nematoda (Smooth Roundworms)

Annelida (Segmented Roundworms)

• More Complex– Bilateral Symmetry– Complete Gut– 3 tissue Layers– Coelomate– Protostomes

• Many soil-dwellers

• Many marine

• Some parasites

Earthworms

PolychaetesLeeches

• Segmentation Specialization• Basic central nervous system• Complex reproductive system • Complex digestive system• Open circulatory system• Simple kidney system

Annelida (Segmented Roundworms)

Annelida (Segmented Roundworms)

Mollusca (Snails, Clams, Squid)• Even More Complex!

– Bilateral Symmetry (some modified)– Complete Gut– 3 tissue Layers– Coelomate– Protostomes

• Diverse!

Mollusca (Snails, Clams, Squid)• Soft bodies, often with a CaCO4 shell

• Complex systems (digestion, reproductive)

• Open circulatory system

• Simple respiratory system (gills)

• Modified Segmentation Specialization– Foot (musclular, locomotion)– Visceral Mass (organs, organ systems)– Mantle (membranous covering & shell secretion)

• CLASS Gastropoda (Snails, Slugs)

Mollusca (Snails, Clams, Squid)

• CLASS Bivalvia (Clams, oysters, scallops)

Mollusca (Snails, Clams, Squid)

• CLASS Cephalopoda (Octopus, Squid)

Mollusca (Snails, Clams, Squid)

Arthropoda (Insects, Crustaceans, Spiders)

• Rather Complex!– Bilateral Symmetry– Complete Gut– 3 tissue Layers– Coelomate– Protostomes

• Very Diverse!

Arthropoda (Insects, Crustaceans, Spiders)

• Hardened Exoskeleton (Protein & Chitin)– Molting to grow

• “Jointed Feet”• Segmentation (often modified through fusion)

– Specialization

• Open circulatory system• Simple respiratory system (gills, book lungs,

tracheal system) • Complex systems (digestion, reproductive)

• CLASS Insecta (grasshopper, fly, butterfly, ladybug, mantis, bee, wasp, etc.)

Arthropoda

Metamorphosis

3 sets of walking appendages

15 Orders!

• CLASS Arachnida (Spiders, Ticks, Scorpions)

Arthropoda

4 sets of walking appendages

Chelicerae (jaws)

• CLASS Crustacea (Crabs, Shrimp, Lobsters)

Arthropoda

Echinodermata(Sea Stars, Starfish, Sea Urchins)

• Somewhat Complex– Radial Symmetry– Complete Gut– 3 tissue Layers– Coelomate– Deuterostomes

Echinodermata(Starfish, Sea Urchins)

• Radial Symmetry is “secondary”– Almost Radial– Larvae are bilateral

• Endoskeleton (hardened calcium plates or spines)– “Spiny-skin”

• Water Vascular System – Hydraulic locomotion,feeding, gas exchange

• Complete Gut– (Seems Incomplete)

Echinodermata (Starfish, Sea Urchins)