All organisms in this group are eukaryotes! Multi-cellular organisms Heterotrophs… ingest other organisms for food

Animals differ in… 1…Body symmetry 2…Cephalization 3…Gut (sac with one opening; tube with 2 openings) 4…Body cavity 5…Segmentation

Sponges Little cell differentiation (10-20 differentiated cells) No body tissues; no internal organs ~ 5,000 species sessile animals Asymmetrical No Mouth/digestive cavity system of water canals/chambers Spicules: shapes and composition vary: siliceous /calcium carbonate

differentiated tissues and organs

Radial symmetry Tentacles; few organs Digestive cavity Mouth exterior opening Hydra, jellyfish, sea anemones and corals 9,000 species 2 tissue layers Free swimming or sessile Tentacles surrounding the mouth Nematocysts (stinging cells) Carnivores

Mouth is first to develop Flatworms, mollusks, annelids, roundworms, arthropods Anus is first to develop Echinoderms and Chordates

Protostomes = mouth develops first Mouth arises from a blastopore Bilateral animals Determinate cleavage (cells are assigned an address) Master Gene Products map out basic body plan forming from 2 to 3 germ layers in embryo Specialized tissues, organs, and organ systems Flatworms, mollusks, annelids, roundworms, arthropods

Platyhelminthes Flatworms (simplest bilateral animals) Cephalized; organ systems; 3 primary tissues Dorso-ventrally flattened One opening = mouth Planarian (free living) Flukes, and tapeworms (parasites) Nematoda Cylindrical animals Front and rear ends tapered Parasitic Rotifera Prey on bacteria and photoautotrophic algae Pseudocoelomates

Annelida …11,000 species …segmented worms …Earthworms and leeches …scavengers …Coelomate …Digestive, nervous, excretory, circulatory systems Mollusca … 60,000 species …snails, chitons, clams, squids, and octopus …Soft bodied …Coelomates …mantle

Arthropoda …1 million + species …crabs, shrimp, mites, ticks, scorpions, spiders and insects …Segmented body …jointed appendages …chitinous exoskeleton …Modified respiratory structures …Sensory structures …Insects have a division of labor among different stages in life cycle

Echinodermata 6,000 marine species Deuterostome sea stars, sea urchins, sand dollars, and sea cucumbers radial symmetry Spiny skinned Water vascular system (tube feet) Chordata Deuterostome All embryos …Notochord …Tubular dorsal nerve cord …Pharynx with gill slits …Tail Anus Craniates …cartilage or bony structure encloses brain Lancets, tunicates, cartilaginous fish, bony fish, amphibians, reptiles, birds, mammals (monotremes, marsupials, placentals)