BIOL 1001 Chapter : CH 3 Outline Fall 2014
Document Summary
Most recent hypothesis about animal phylogeny (figure 32. 11) Concept: 33. 1: sponges are basal animals that lack true tissues. Concept 33. 2: cnidarians are an ancient phylum of eumetazoans (true tissue layers) A wide range of sessile (don"t move as adults) and floating forms including jellyfish, corals, and hydras. Simple diploblastic (two tissue layers), radial body plan: body plan is a sac with a central gastrovascular cavity. Single opening serves as both mouth and anus7. Mesoglea layer (jelly of jellyfish) between epidermis and endodermis (gastrodermis) Medusa form moves freely in water by passive drifting and contractions of the bell. Cnidocytes: unique cells that function in defense and the capture of prey, why we get stung by jellyfish. Stimulus causes the cell to evert releasing thread. Cnidarian diversity (table 33. 1 and figure 33. 7) (scyphozoa-big) (anthozoa-smaller) Concept 33. 3: lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms (coelom open body) Alimentary canal with separate mouth and anus.
