Branchiostoma is a ciliary or filter feeder, like an ascidian. The animal leads a sedentary life buried in sand .Food particles are filtered from the current of water entering pharynx through mouth and finally going out through atriopore.The atriopore closes and the transverses muscles oc the floor undergo sudden contraction. This sets up a reversal of water current or rejection current ejecting out forcefully through through the enterostome and mouth. Pharynx plays the most important part in food collection. In side pharynx the food particles get entrapped in mucus secreted by the glandular tracts of endostyle and by pharyngeal epithelium. The endostylar cilia and the frontal cilia of gill bars beat upwards so that mucous sheets laden with food particles move dorsally to the epipharyngeal groove. The cilia of epipharyngeal grrove beat backwards moving the food-laden mucus into the oesophagus in the form of a narrow food cord.
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