First Animals Soft bodies so trace fossils only Sponges Jelly fish Worms Late Proterozoic

Time Line of Animal Evolution 1st Fossil evidence of animals 570 mya = Proterozoic Eon Massive adaptive radiation of animals called the Cambrian Explosion signaled the start of the Phanerozoic Eon Cambrian Explosion due to increased oxygen for aerobic respiration more energy = larger more mobile animals move into new areas and adapt

Phanerozioc begins with Cambrian Explosion

Evolution of Animals Some type of Protist mutated to become multicellular Multicellular organisms start as a single cell (zygote) and grow into organisms with groups of specialized cells performing different functions All animals are multicellular

Proterospongia = Protist & common ancestor to all animals?

Proterospongia: Colonial, Unicellular Protists

Sponge collar cells

Phylum Porifera Sponges Only 3 types of cells Collar cells Amoebocytes Epidermis cells (protective outer layer of cells) No tissues Cells held together by jelly like substance Skeleton make of proteins Asymetrical

Intracellular digestion (like protists) Collar cells take in food by endocytosis Food digested in food vacuoles Some food passed to amoebocytes Amoebocytes carry food around sponge body. (circulaton) http://shapeoflife.org/video/phyla/sponges-origins

All other Animals have True Tissues & symmetry

Phylum Cnidaria Have stinging cells = cnidocytes Have tentacles Radial symmetry = sit and wait predator 1st nervous system = nerve net & eye spots

Digestion & Circulation Have gastrovascular cavity for digestion & circulation 1st extra cellular digestion – cells lining GVC secrete digestive enzymes Evolutionary advantage = can eat larger food Cillia push digested food around the GVC GVC branches into all tentacles: comes near all cells

All other animals have Bilateral symmetry

Flatworms had it FIRST!! Bilateral symmetry = evolved to facilitate directional motion = 1st mobile predator Cephalization – development of a head Ganglia: bundle of nerve cells make up a pre-brain Nerves concentrated at ‘head end’ since sensory cells were concentrated at that end Sensory nerves formed bundles = ganglion Eyespots detect light, Auricles detect chemicals ‘smell’ 2 nerve cords transmit info to rest of body

Evolution of Bilateral Symmetry

Flatworm primitive Traits Central mouth and GVC http://vimeo.com/37282961

Free-living Flatworms = Class Turbellaria Marine Fresh-water

Flukes = Class Trematoda Parasites of blood and liver

Swimmer’s Itch =Schistosoma

Tape Worms = Class Cestoda

Human Tape Worm Sources =Under cooked Prevention Beef (N. America) Pork(S. America) Fish (Asia) Prevention Cook your meat!!!

All Animals more advanced that flatworms have a body cavity Provides room for organs to develop Body Cavities are called coeloms

Types of body cavity (coelom) Acoelomate Pseudocoelomate Coelomate

Round Worms = Phylum Nematoda 1st Animal with a body cavity =pseudocoelom Fake body cavity – just a space between layers.