Essay Question Microphagy is feeding on very small particulate of ...

Essay Question Microphagy is feeding on very small particulate of food and is a common feeding strategy in many of the animals that we have looked at during the course. What are common problems animals encounter when the use this feeding strategy and how are they solved? Discuss this using two protostomes, one deuterostome and a parazoan in your answer. Microphagy is the earliest form of feeding; filter feeding. Protostomes : (Mollusc) Clam and Bryozoans Clam: • Incurrent and excurrent siphons • water passed over ctenidia for feeding and respiration • clams filter feed by drawing in water containing food using an incurrent siphon. The food is then filtered out of the water by the gills and swept toward the mouth on a layer of mucus. The water is then expelled from the animal by an ex-current siphon Bryozoans: • Cilia trap food pass to mouth • Ciliated lophore tentacles draw in water to the mouth of the bryozoans • From the mouth it is digested in the cardiac stomach, cecum (area where is diffuses easily to other organ; near the repoructive organs) and then pyloric stomach and intestine finally Deuterostome: Cephlachordates (Brachiostoma) • water through pharyngeal slits • food from the water becomes stuck in the mucus lining the pharynx • carried to the intestine by ciliary action • filter feeding animals make use of mucus to capture the food and cilia to transport it Parazoan: Porifera Sponge • filter-feeding by means of a water-canal system

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Asconoid least common water passes through porocytes (doughnut shaped cells) into spongocoel (inner cavity) lined with choanocytes food is captured, water exits via osculum Syconoid water enters incurrent pores, enters radial canals radial canals lined with choanocytes for catching food, water exits via spongocoel and osculum Leuconoid small chambers for choanocytes water flows through incurrent pores to canals and multiple chambers, then to excurrent canal