“Chew All Your Food Dear…. Inside their digestive system they have a unique stomach that is called the GASTRIC MILL. The gastric mill is found in crabs, lobsters, crayfish, barnacles, krill, and many others. These invertebrates don’t have teeth in their mouth to grind their food, so they process it a bit differently.

Crab: Crabs eat mainly dead plant and animal matter, although some graze on algae and others are predatory. They use their two sharp claws to tear and shred food. The food is passed to the mouth, where it is cut into even smaller pieces by the mouthparts.

Tell the students that the swimmerets have three functions. They help the crayfish swim, they move water over the gills for respiration, and on the female they hold the larva.

In the male, its function is to guide the sperm toward the female during copulation; as such, it will be enlarged, and pointed anteriorly in the male.

Uropod: swimming appendage of the crayfish. Telson: last segment of the abdomen of a crayfish. Segment: ring of the abdomen of a crayfish.

Crayfish Parts and Functions

Crayfish are omnivorous, eating just about anything they can find or catch, dead or alive. Large food is held and torn to pieces in the large pincers and conveyed to the mouth by the smaller specialized legs near the head. That’s what crayfish mostly do: loaf all day and look for food all night.

The swimmerets of crayfish serve a function in posture control and beat rhythmically when the animals swim forward, ventilate their burrows or females aerate their eggs 5, 6.

Crayfish have external fertilization (Hamr, 2002). As is well known, there are differences between the crayfish families in their genital morphology (e.g. summarized in Reynolds and Souty-Grosset, 2012).

Learning > Species > Crustaceans > Crayfish Glossary

Focus on the head, you may notice small appendages around the mouth. These are called the MAXILLIPEDS, and there are three sets, one on top of the other. These appendages help the crayfish manipulate food. The MANDIBLES of the crayfish are similar to the jaws of humans.

Crayfish mate in the early spring and females carry the fertilized, developing eggs inside their bodies for 4 to 6 weeks. These developing eggs are then transferred to the outside of the female’s body and glued via an adhesive called “glair” to the female’s tail. The eggs then hatch by the end of spring.

Therefore, the digestive gland has two functions – digestion and storage. The digestive system works in the following way. Crayfish use their claws to catch, crush, and tear apart the food. When, through the passage in the mouth, the food goes to the Esophagus (part of the digestive tract between the mouth and the stomach).

Note: To be precise, the gills are located on the outside of the body cavity in a space between the body wall and the carapace. The carapace does not fit tightly against the body of the crayfish, there is a space between the body and the carapace so water can circulate through the gills.

The Reproductive System of Crayfish In male crayfish, testes produce spermatids that are transported to and accumulate in the vas deferens. The testes (paired and soft organs) are located near and beneath the heart. Each of them includes numerous tiny tubes, called seminiferous tubules.

Secretes enzymes to break down the food and stores fats and glucose. They are involved in opening and closing the mandibles. The central nervous system of crayfish. It also activates the swimmeret system. Responsible for extending the abdomen or straightening it. They are located on top of the abdomen.