Biology 3229F/G Lecture Notes - Lecture 7: Brittle Star, Keystone Species, Echinoderm
10 Dec 2016
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Document Summary
Similar to sea water: mutable connective tissue. Echinoderms on far right of the tree a very derived group. Closely related to chordates echinoderms aren"t chordates. All marine/brackish water no freshwater echinoderms, all salt water. Type of skeleton make for a good fossil species; come up readily in fossil record because they have calcified skeleton. Asteroidea (sea stars), echinoidea (sea urchins), crinoidea (sea lilies), ophiuroidea (brittle stars), holothuroidea (sea cucumbers) Adult: pentaradial 5 axes of symmetry *few exceptions. In the larval stage, the larvae are bilaterally symmetric distinct mouth and anus. Water-vascular system series of connected tubes it uses to move or feed. Locomotion using wvs using innervation (motor neurons), ampullar muscles pumped back into ampulla) manipulate the pressure within the system allowing it. Tube feet can organize the way they move it and coordinate, but they don"t have. Ossicles little bone-like fragment made from calcium carbonate that form together.
