BIOL 112 Lecture Notes - Lecture 33: Obelia, Trematoda, Catenulida
Document Summary
3:33 pm: invertebrates - lack a backbone, porifera, cnidaria, placozoa, acoela, ctenophora, lophotrochozoa. Water is drawn through the pores into a central cavity, the spongocoel. Many have branched water canals and several oscula. True tissues - group of similar cells that act as a functional unit and are isolated from other tissues by membranous layers. Choanocytes - flagellated (collar cells) lining interior of spongocoel. Engulf bacteria and other food by phagocytosis. Gas exchange and waste removal through diffusion. Totipotent - become any type of sponge cell as needed. Spongin - proteins used to make flexible fibers. Hermaphrodites - each individual functions as both male and female. Sequential - first one sex and then as the other. Sperm released into the water current, drawn into neighboring female. Settle on suitable substrate and develop into a sessile: cnidarians adult. Diversified into a wide range of sessile and motile forms.