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What Happens to the Digested Food in a Crayfish?

The diverse crayfish diet includes live or dead vegetation, tadpoles, fish eggs, snails, numerous insects and algae. Their various environments, from North America to Europe to South Asia, dictate dietary choices. Their digestive anatomy remains consistent despite their home region. Crayfish are heavy feeders, usually found in freshwater. As crustaceans, crayfish digestive systems appear and function in a manner similar to lobsters.

Anatomy of the Digestive System
- The crayfish digestive system is nearly identical to that of a lobster.
  
  Crayfish consume food through the mouth's mandibles. The digestive process begins here, as the crawfish's mandibles break apart the food items. The particles continue from these mouthparts to the internal system, where the nutrients are absorbed, true digestion takes place and, finally, waste is expelled. The cardiac and pyloric stomaches (foregut), followed by the digestive gland and intestine (midgut) and rectum (hindgut) make up the internal digestive system.
Foregut
- The strong crayfish chelipeds attack and grab prey.
  
  Once a crayfish chews its food, the particles pass through the esophagus, where the sensory glands "taste" the food. The food then enters the cardiac stomach, where initial enzymes that originate in the next organ (pyloric stomach) travel backwards into this first stomach. With the help of these enzymes and internal barbs, the cardiac stomach further breaks up the particles. The food particles then enter the pyloric stomach, where a tooth-like "gastric mill" finely grinds up the particles, sending the smaller ones to the next region (the midgut) and sending back the larger particles for more grinding.
Midgut
- Crayfish bodily fluid is called "hemolymph."
  
  Those particles small enough to exit the pyloric stomach enter the midgut region. Above this abdominal tract, the dorsal abdominal artery extracts nutrients through blood vessels and into the "hemolymph," or the bodily fluid of crustaceans and other invertebrates. The midgut's mucous membranes encase the remaining particles into pellets, which the midgut then forcefully pushes into the hindgut.
Hindgut
- An efficient, effective digestive system assures that the crayfish receives ample nutrition.
  
  The hindgut, consisting of the rectum and anus, dispose of the digested and undigested particles not absorbed by the crayfish. Contractions complete the food item's digestion, excreting the waste through the anus.

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