BISC 121Lg Chapter Notes - Chapter 33: Gastrovascular Cavity, Hydrostatic Skeleton, Mesohyl
Document Summary
Invertebrates- animals that lack a backbone: >95% of known species. Chapter 33: sessile, sedentary, and lack true tissues, can be mms to meters long, mostly marine, filter feeders- filter out food particles suspended in surrounding water and draw it through their bodies. Spongocoel- central cavity pores that water is drawn in through. Osculum- large opening water flows back out through: basal species, choanocytes- have flagella and line the inner wall of spongocoel. Very similar to choanoflagellates: mesohyl- gelati(cid:374)ous regio(cid:374) that separates a spo(cid:374)ge"s 2 layers of (cid:272)ells. Amoebocytes- have pseudopods, move through mesohyl, take up food from water and choanocytes, digest food, carry food to other cells, manufacture tough skeletal fibers (made of calcium carbonate, silicon, or sponging) Totipotent (can become other sponge cells: hermaphrodites- function sexually as both a male and a female. Function first as one sex and then as the other.
