WFSC 302 Lecture Notes - Lecture 2: Germ Layer, Jellyfish, Animal
27 Jan 2016
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O eukaryotic organisms: divided between about thirty different phyla, animals" relationships are traditionally based on embryological and anatomical characteristics. Recent evidence from dna is changing our understanding of these relationships (cid:1) Metazoa: a new term for multicellular animals: porifera. No germ layer, true tissue, or organs. Where vertebrates fit into the tree of life. Has three germ layers (cid:1) (cid:1) (cid:1) This phylum includes the acorn worm: the acorn worm is a marine invertebrate that filter feeds and lives in u-shaped barrows in the sand. This phylum is considered the sister group to either the phylum. Acorn worm: 70 species known in the world, fragile little bags of sand , the head looks like an acorn. Amphioxus (cephalochordate) tells us about our own brains. Deep within our genes, there are similarities between us and. Amphioxus live in the sand of the ocean floor. They have a nerve cord that swells on the anterior end, kind of like a simplified brain.
