Bio2 Lecture 4

Bio2 Lecture 4 - Bio2 Lecture 4 1/28/05 Phylum echinoderms...

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Bio2 Lecture 4 1/28/05 Phylum echinoderms - Sea cucumber, sea stars, - Circulatory system poorly developed - Bilaterally symmetric, as larvae, but as adults they become more radial symmetric - No cephalization, have a lifestyle of a radial symmetric animals, even though they are originally bilaterally symmetric - Have a water vascular system, modification of the ceolum, water from sea enters system, through siv plate, gets rid of access stuff, goes into a ring canal, then into radial canals that run through the arms, then you have tube feet. o Tube foot is connected to a bulb object called ampulla, from radial canal there is a valve that goes into the ampulla, then muscles that contract which forces water in ampulla to exit through the tube foot. This causes the tube foot to extend, and lets it grab onto objects. Muscles in the tube foot then can contract which will cause it to get smaller. Phylum Hemichordata - not in lecture exams Phylum Chordata - includes 2 major subphyla, which have invertebrates, then ours which is the vertebrates - structures that unite us are o notochord – made of cartilage and a supporting rod for the body, stiff enough to support body yet its still a bit flexible. o hollow dorsal tubular nerve chord – in ventral position and solid, starting from when you were young. Your brain is hollow and filled with fluid, so is your spinal chord o pharynx with gill slits – had as an embryo and still have vestiges, the holes in your ears are gill slits, have supporting bars of cartilage, 3 bones in little ear is derived from gill bars, eventually became used for respiration(in
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Bio2 Lecture 4 - Bio2 Lecture 4 1/28/05 Phylum echinoderms...

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