BISC 120Lg Lecture Notes - Lecture 17: Gastrovascular Cavity, Ctenophora, Gastrointestinal Tract
20 Apr 2016
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Eumetazoa: animals with true tissues: basal eumetazoans are diploblastic and generally have radial symmetry. Bilateria: most animal phyla belong to this clade: bilaterally symmetric, triploblastic (three prominent germ layers, the cambrian explosion was the primary rapid diversification of bilaterians. Bilateria: 3 major clades: deuterosomia, lophotrochozoa, ecdysocozoa: have an exoskeleton. *all animals part of bilateria are invertebrates except for a single phylum: chordata. It is not recognized as a separate lineage that diverged before the 3 main bilaterians clades. Have a basic body plan which is a sac with central digestive compartment called the gastro vascular cavity. They are considered predators and have nemocyst which are poison. (like a jelly fish sting) A single opening acts as the mouth and anus. Very similar t cnidarian: it is diploblastic and has radial symmetry. When prey contacts the tentacles of comb jellies specialized cells burst open covering the prey with sticky threads: lophotrochozoa, platyhelminthes: are either free living or parasitic.
