COMM 1076 Lecture Notes - Lecture 11: Gastrovascular Cavity, Pearson Education, Mesohyl
Document Summary
Invertebrates animals without a backbone account for 95% of known animal species and all but one of the roughly 35 animal phyla that have been described. More than a million extant species of animals are known, and at least as many more will probably be identified by future biologists. Invertebrates inhabit nearly all environments on earth, from the scalding water of deep-sea hydrothermal vents to the rocky, frozen ground of antarctica. Water is drawn through the pores into a central cavity, the spongocoel, and flows out through a larger opening, the osculum. More complex sponges have folded body walls, and many contain branched water canals and several oscula: sponges range in height from about a few mm to 2 m and most are marine. The sponge body does contain different cell types: sponges collect food particles from water passing through food-trapping equipment.
