ECON 2000 : Exam 4
Document Summary
Definition: invertebrate (soft bodied, no rigid internal structure: what change on earth made it more favorable for animals to come into existence? (change in atmospheric composition - increased oxygen concentration due to photosynthetic bacteria, [and subsequent primary producers]) Phylum porifera: simplest multicellular organisms, no true tissues or organs, sessile, suspension feeders (flagella help circulate water, sponges. Phylum cnidaria: specialized tissues (allow for coordinated activities, stinging cells ("nematocysts , radial symmetry, 2 possible body forms: opolyp ( primarily asexual reproduction) omedusa (sexual reproduction, ex: jellyfish, corals, sea anemones. Class hydrozoa: diverse body forms, ex: siphonophores oex: portuguese man-o-war. Class anthozoa: solitary or colonial polyps, lack medusa stage, ex: corals, sea anemones. Phylum ctenophora: entirely planktonic, marine, radial symmetry, colloblasts (sticky cells for capturing prey, 8 bands of cilia for propulsion. "blind (one-way) gut otremetoda ("flukes ) ocestoda (ex: tapeworms) Definition: possess true coelom (body cavity) - digestive tract separate from body wall.
