AGRC1020 Lecture Notes - Lecture 10: Gastrovascular Cavity, Mesohyl, Scyphozoa
6 Aug 2018
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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. Concept 33. 1 sponges are basal animals that lack. Sponges (phylum porifera) are so sedentary that they were mistaken for plants by the early greeks. Living in freshwater and marine environments, sponges are suspension feeders. The body of a simple sponge resembles a sac perforated with holes. 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.
