ZOO 2700 Lecture Notes - Lecture 27: Collagen, Crinoid, Muscular System
28 Mar 2018
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Document Summary
Echinodermata sometimes referred to as non-chordate deuterostomes. Protostomes: anus transforms into mouth (closed system, solid mass of meso derm that starts to form coelom. Deuterostomes: forms mouth, fairly large open coelom. Apomorphies: enterocoely, has to do with formation of the coeloms, blastopore into anus, suspension feeding, done by pharynx- gill slits. Pentamarous symmetry: not homologous to cnidarians. Connective tissue: mutable connective tissue: squishy at first but when squeeze can harden, does this by changing of tissue in the skin in a very short period of time. Claim: 2 groups, sea stars and brittle stars, and sea cucmber and sea urchins: ophiuroidea sister group to asteroidean, and holothuroidea sister group to echinoidea. Elastic collagen fibres: link together, do this in a short period of time, upon touch, a sensory input stiffens fibres, different from muscle fibres, does not involve calcium, histamine involved in muscle contraction in sea cucumber. Cirri (small feeding structures) (cid:498)sea-lillies(cid:499) stalked (sessile)
