BISC 120Lg Lecture Notes - Lecture 18: Eumetazoa, Animal, Blastula
22 Mar 2016
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***********sponges are basal animals that lack true tissue (thus, not part of eumetazoa) Most animals reproduce sexually with the diploid stage usually dominating life cycle. Zygote -> cleavage -> blastula -> gastrulation endoderm: digestive; inner most layer radial symmetry: think circular bilateral symmetry: lobster bilaterians: longitudinal plane of symmetry and specialized in internal organ systems. Tissues: collections of specialized cells isolated from other tissues by membranous layers germ layers: give rise to (look at slide) Sponges are basal animals and lack true tissue. Eumetazoa is clade of animals with true tissues. All bilateria are triploblastic (have ectoderm, endoderm, and mesoderm) Uid or air- lled space between digestive tract and outer body wall. True body cavity: coelom - derived from mesoderm vertebrates: 365 mya. All molluscs have a similar body plan with three main parts.
