BIOL 330 Lecture Notes - Lecture 2: Facial Skeleton, Sensory System, Parathyroid Gland
14 Feb 2017
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What are the 3 subphyla of chordata: vertebrates, cephalochordates, small marine animals, urochordates (tunicates, small marine animals. What are the 4 main chordate characteristics: notochord. * cell layers and tissues, nervous system with neurons* cnidarians (ectoderm, endoderm) triploblasts (ectio, meso, endoderm; bilateral symmetry, symmetrical gut; anterior head. * coelom: split in mesoderm forms inner body cavity. Protostomes: blastopore (1st opning in the embryo) becomes the mouth. Deuterostomes: blastopore becomes the anus (second opening: mouth) chordata. Most adults are sedentary (probably a derived form: sequential contraction of myomeres (striated muscle fibres on the sides of body) Incompressible notochord (prevents body from shortening when myomeres contract) Respiration occurs through the skin surface; gill slits are used to filter feed: myomeres, analogous circulatory system, vertebrate-like tail fin. Animals that have vertebrae serially arranged to form a spinal column*; these replace the notochord after the embryonic period. Whole-animal level transition from non- vertebrate chordate.
