BSC 196 Lecture Notes - Lecture 10: Mesoglea, Body Plan, Sea Pansy
Document Summary
First appeared in the oceans around 600 mya. Earliest probable animal fossils date to the late precambrian period (ediacaran biota, 610 mya). Subkingdom parazoa: animals without a mouth, digestive cavity, true tissues, or symmetry. Subkingdom eumetazoa: animals with a mouth, digestive cavity, and true tissues: clade radiata: animals with radial symmetry, clade bilateria: animals with bilateral symmetry, 5,000-10,000 known species. Subkingdom parazoa: a monophyletic sister group to all other animals. Lack true tissues, mouths, digestive cavities, organs, and symmetry. Sessile filter-feeders with a body modified into a system of water canals. Feed on bacteria and suspended particles: mostly marine, some in freshwater. In bloomington-normal sewage system: common in rocky benthic (bottom) habitats and coral reefs, class hexactinellida: glass sponges. Typically hard bodies made of silicon: class calcarea: calcareous sponges. Typically hard bodies made of calcium carbonate: class demospongiae: most specious group of sponges.
