BIOL 2001 Lecture Notes - Lecture 4: Water Vascular System, Vertebral Column, Thyroid
23 Feb 2016
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Lecture 4 - overview of major phyla iii. Starfish, sea urchins, sea cucumbers, brittle star, sand dollars. Adults have radial symmetry but the larvae are bilateral. Body equipped with complex network of fluid filled canals forming the water vascular system o. Can regenerate parts of their bodies (mainly limbs) Generates movement through changes in pressure throughout the system. Formed by the invagination of the neural plate (derived from the ectoderm) Dorsal to the notochord (nerve chord is ventral to the gut in non-chordate animals) Dorsal, hollow nerve chords (protostomes ventral and solid) o o o. Notochord: gives support to the body (lost in vertebrates - present in embryo) o. Connective tissue that might have another sheet of collagen (both give the stiffness of o o o the structure. Inside filled with cells that are hollow (vacuole present - called notochordal cells) If it were compressible, the body would just shrink when the muscles used for movement contracted.
