Sunflower Starfish
The Sunflower Starfish swallows its prey whole, and start to digest it in their cardiac stomachs. Shell halves and other inedible materials are ejected through their mouths. The semi-digested fluid is passed into their pyloric stomachs and caeca where digestion continues and absorption ensues. When the prey is a clam or other bivalve, the starfish pulls with its tube feet to separate the two halves slightly, and inserts a small section of its stomach, which releases enzymes to digest the prey. The stomach and the partially digested prey are later retracted into the disc. Here the food is passed on to the pyloric stomach, which always remains inside the disc. The retraction and contraction of the cardiac stomach is activated by a neuropeptide (any of a group of compounds that act as neurotransmitters and are short-chain polypeptides), known as NGFFYamide.
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