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