Deuterostome Body Plans

What are the common body plans in deuterostomes? How have they been modified in different groups?

Deuterostomes are bilaterally symmetric (one plane of symmetry), triploblastic (three tissue layers), and are all coelomates (completely lined body cavity). They all also undergo similar embryonic development, with the initial pore in the embryo becoming the anus. Besides these similarities, however, all other features are varied throughout this group.

Although echinoderms are bilaterally symmetric in the larval stage, they display five-sided radial symmetry as adults. They also developed an endoskeleton and a water vascular system. The endoskeleton is a deposit of calcium carbonate inside the organism’s skin that provides protection and support. A series of tubes and chambers make up the water vascular system which moves sea water and particles through the body by beating cilia.

The chordates have pharyngeal gill slits, a dorsal hollow nerve cord, a notochord, and a post-anal tail. The gill slits are openings into the throat to help with suspension feeding. The nerve cord, notochord and tail coordinate muscle movements along the body length to function in movement.


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