ZOO 2700 Lecture Notes - Lecture 21: Ventral Nerve Cord, Kinorhyncha, Hydrostatic Skeleton
28 Mar 2018
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Document Summary
Segmentation: segmentation found in other groups though, evolved through the chordates, annelids were lumped together with other groups because of segmentation. Cryptobiosis: a form of diorstage (occurs in insects, state in the life when the metabolism is essentially shut off, ex. Egg or other part of reproduction that the insect is protected- can last for decades, like time capsules that allows us to analyze the past: forms a tun. Reduce metabolism, to survive adverse climates; become clinically dead but just produces enough to survive. Some of the water in the organism is replaced by proteins, anti-freeze proteins: ex. Stylet: moulting, during the moult cycle, the stylet is lost. Nervous system is bilateral symmetric, clear bilateral symmetry, left and right side in terms of nerve cords. Cylome very compacted and only seen in reproductive regions/organs. Mating between separate sexes; male a lot smaller than female; reproduction timed with moulting cycle.
