Commercial Fisheries News - December 2001

Food consumption: Claws to gut

Lobsters do not use their claws to actually eat.In fact,it is nearly impossible for them to pass food to their mouthparts using these appendages due to the position and bulk of the claws. Instead,a lobster uses its claws to capture and disable the assorted prey that makes up its diet.

During foraging,a lobster uses its crusher claw to break open hard-shelled food such as mussels,clams,and crabs. The lobster uses its seizer claw to grab prey such as fish and squid.Once the prey have been seized or crushed by the major claws, the pinchers on the next pair of legs taste and pick apart the food.The smaller legs then pass morsels of flesh to the mouthparts.

Most of the lobster mouth is located on the outside of the face,where multiple feeding appendages tear,sift,and macerate meat.The outermost pair of mouthparts is lined with long sensory hairs for tasting and is armed with razor-sharp teeth for gripping and tearing off bits of food.

Lobsters hold food in place with the legs and tear off shreds by gripping the meat with the teeth located on the outermost mouthparts and jerking their heads backward.

Four additional pairs of mouthparts wave and flutter to guide the food to the jaws. The rock-hard lobster jaws open and close from side to side, rather than up and down. Beyond these crushing mandibles, the lobster has fleshy lips and a short esophagus through which food travels to reach the stomach.Even in very large lobsters, the stomach is less than an inch away from the mouth.

Mastication takes place in the stomach where two sets of teeth grind food. Enzymes secreted by the tomalley aid in digestion.The stomach and esophagus are lined with uncalcified chitin that is shed during molting. A portion of the stomach is calcified to form the gastric mill. Gastroliths along the stomach lining store calcium to quickly harden the new shell after molting. The remainder of the gut is made up of intestine,which ends at the opening on the underside of the end of the tail.

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