BIO 2135 Lecture Notes - Lecture 14: Water Vascular System, Tube Feet, Hydrostatic Skeleton
17 Apr 2016
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Gastrulaion: a single epithelial layer invaginated inwards to make a second digesive epithelium - endoderm - which is the gut. The opening to the gut is the opening to the digesive tract blastopore. Body cavity that instead of back-illing mesoderm from the lip of the blastopore, a litle bubble of mesoderm forms of the enteron and ills the space in between. Problem: it occurs in lophophore protostome lineage so it can"t be used to deine deuterostomes. Uniquely shaped larval issue around a bell (with an organism suspended in it) with an anus and mouth. Can shater its arm so it can get away. Feeds with tentacles that extend up from its body and place food on tentacles to its mouth. When atacked by a predator they open up the anal vent and throw out their whole lower digesive tract onto the predator. Dipleurula larvae setles to the ground and becomes radially symmetric (so radial symmetry is a derived trait)
