BIO153H5 Study Guide - Final Guide: Nephridium, Zygote, Hydrozoa
Document Summary
Sponges are basal animals that lack true tissues. Sponges are sedentary and were mistaken for plants, most are marine. Sponges are suspension feeders : capture food particles that are suspended in water and pass through their body which contains pores. Water is drawn through the pores from a central cavity known as the spongocoel, and then flows out of the sponge through a larger opening called the osculum. Sponges lack true tissue but have other cell types: >> choanocytes : flagellates that line the interior of the spongocoel . >> amoebocytes : use pseudopodia to take up food, digest it and carry nutrients to other body cells. Also manufacture tough skeletal fibers within the mesohyl which are sometimes make up of calcium carbonate or silica (sharp called spicules). Other times these fibers are made out of flexible proteins called spongin. The body contains two layers of cells separated by the mesohyl (gelatinous region).
