SLE204 Lecture Notes - Lecture 6: External Fertilization, Sensory Neuron, Tube Feet

• School: Deakin University
• Department: Science, Engineering and Built Environment
• Course: SLE204
• Professor: Anneke Veenstra

Document Summary

Rough, spiny surface with ossicles small calcareous plates. Aid in food capture and move food towards mouth. Protect papulae (dermal branchiae or skin gills) Papulae (dermal branchie or skin gills) -> gas exchange. Madreporite (sieve plate) filters water; on aboral surface. Have pyloric caeca (digestive glands) in each arm. Coelom fluid filled transports o2 and co2; excretion of nitrogenous waste. Nervous system: radial nerve and nerve ring (image) Ocelli pigmented eyespots at tips of arms. Others scattered over body surface for touch, chemicals and light intensity. Mostly external fertilization; paired gonads in each arm. Regeneration: can replace lost arms, or break off injured parts and regenerate (autotomy) Tube feet (no suckers) -> for feeding only. 5 pairs bursae (pouches next to mouth) for gas exchange. Water vascular system; regeneration (similar to sea stars) Fused dermal ossicles from rounded shell (test) Longer digestive tract to digest algae and detritus. Long movable spines extend from test assist in locomotion.