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)