Animal Groups Bio 126 – Nature Study

Sponges Filter feeders Simplest animals No muscles, no nerves,brain Very flat, small in cool California waters Sessile as adults

Cnidarians Sac-like gut (one opening) Tentacles with stingers (nematocysts) Have simple muscle-like contractile cells Have a simple sensory cells in a simple nervous network Have Polyp and Medusa forms Corals are Polyps forms Sea Jellies are medusa forms

Nematodes – Roundworms Bilateral symmetry Cephalized (has a head) Flow-through digestion Hollow (pseudoceolomate) body Common in Soil Parasites on plant roots Some are human parasites too !

Mollusks- Mantle May secrete shell -exoskeleton Muscular Foot Gills Snails have scraping radula

Types of Mollusks Gastropods – Stomach-foot Snail, slug Nudibranch Chitons – 8 plates Bivalves Clams, scallops, oysters, mussels Cephalopods – Head-foot Squid, Octopus Foot divided into tentacles Most intelligent non-vertebrate

Annelids- Earthworms Circulatory system Segmented worms Hermaphrodites Cuticle Also: Leeches Pile worms

Arthropods Hardened exoskeleton of chitin Molting between stages Segmented body plans Jointed appendages Division of labor in lifecycle Larvae Metamorphosis

Arthropod groups Insects Spiders & mites Crustaceans Crabs, crayfish Barnacles Millipedes & centipedes

Echinoderms – spiny skin Gone back to radial-like symmetry Hardened spine skin Internal skeleton Tube feet Water vascular system Sea stars, sea urchins, sand dollars

Tunicates – sea squirts Cellulose tunica surrounds animal Adult a sessile filter feeder Larvae swims, has tails, nervous system

Cartilaginous fish Sharks and rays Bony fish Many types

Amphibians Still need water to breed Juvenile still a fish Thin, moist skin Tetrapods Walks like a fish out of water

Reptiles Scaly skin, resists drying out Amniote eggs – On land, in a moist nest in soil Leathery shell internal fertilization Kidneys – conserve water

Aves- the birds Warm blooded Feathers for insulation, later for flight Hollow bones Efficient respiration Intelligent Amniote eggs with hardened shell

Mammals Warm blooded Hair for insulation Nourish young with milk Intelligent Long Parental care period Learned behaviors Specific dentition