They have three distinct mouthpart types. The mandibles are used for the crushing of their food. While the maxillae with maxillary palps and the three sets of maxillipeds are used by the crayfish to manipulate their food into their mouths.
They have two pairs of antennae, mandible-type mouthparts (of different evolutionary origin than mandibles in insects), and other mouthparts which include two pairs of maxillae and three pairs of maxillipeds, all of which are formed from modified appendages.
In addition to its walking legs and chelipeds the crayfish has five pairs of smaller limbs called swimmerets. The swimmerets are attached to the underside of the abdomen and are used to identify the gender of the crayfish.
The exoskeleton, or body covering, is thin but tough. The front pair of the five pairs of legs have large, powerful pincers (chelae).
These appendages help the crayfish manipulate food. The MANDIBLES of the crayfish are similar to the jaws of humans. They are strong and can break the hard shells of many aquatic animals. Crayfish can eat fish, other invertebrates like crabs and shrimp.
The mandibles, or jaws, crush food by moving from side to side. Two pairs of maxillae hold solid food, tear it, and pass it to the mouth. The second pair of maxillae also helps to draw water over the gills.
Anus: outlet of the digestive tract. Flexor muscle: muscle that bends the tail of the crayfish. Digestive gland: glandular organ that produces digestive enzymes.
The Gastric Mills of Crayfish and Other Crustaceans
Crayfish use gastric mills to help break down their food.
The body is divided into three tagmata, cephalon, thorax, and abdomen. The head and thorax are fused into a cephalothorax and may be difficult to distinguish.
Note the jointed appearance and the shape of these appendages. The abdominal appendages consist of five pairs of pleopods (or swimmerets) and one pair of uropods. The pleopods of the female are all similar (and serve to carry the eggs), except that the first pair is reduced.
SWIMMERETS in the crayfish are the paired ventral abdominal appendages which beat in a metachronal rhythm during behaviours such as swimming and burrow ventilation. Each swimmeret is driven by alternating bursts of impulses in antagonistic power- and return-stroke motoneurones.
Do crayfish have leg joints? How many? yes, they have 10!
In the parastacid crayfish, the typical gill comple- ment consists of 12 developed and 5 rudi- mentary gills, whereas the genus Cherax has 21 plus a rudimentary epipod (Hobbs, 1974), which is the same as for the redclaw cray- fish.
Note that each pair of antennae are biramous appendages. Examine the telson and uropod. How does the crayfish use these biramous appendages to escape predators? Using a probe, try to find the mouth and anus.
Crayfish, like all large crustaceans, use gills to gather oxygen. Found in the sides of the body and at the base of each leg, these gills behave like those of most aquatic creatures, pulling oxygen into the bloodstream as water passes through them.
Breeding in crawfish tends to occur in the fall, when they reach sexual maturity. Female crawfish display different reproductive preferences based on certain male traits. Females prefer large claws in males; males use their claws (chelae) against opponents and to attract, secure and position females for mating.
crayfish info. Crayfish are invertebrates. That means they don’t have bones, but they do have an exoskeleton to protect their inner body parts. The crayfish have jointed legs to walk and pick up food.
|Crayfish Temporal range:|
|Superfamily:||Astacoidea Latreille, 1802 and Parastacoidea Huxley, 1879|
|Astacoidea Astacidae Cambaridae Cambaroididae Parastacoidea Parastacidae|
North America is home to 390 native species of crayfishes, 75% of the world’s total. No native crayfish occur in Arizona or the Colorado River basin of western North America; however, they have been widely introduced to this landscape and have become widespread and abundant throughout the Colorado River basin.
Crayfish bodies are divided into three parts; the head, the thorax (the section that contains the legs), and the abdomen (or the tail, which is the edible part of many large crustaceans including crayfish, prawns and lobsters).
The circulatory system of the crayfish is an open system where the blood is contained in vessels for only part of the system. The heart is located in a pericardial sinus located in the upper part of the thorax (a sinus is a sac or cavity). The heart pumps the blood into the arteries.
Crayfish may be kept in an aquarium or similar water-tight-container. A 30-gallon aquarium will house up to six large crayfish. … The water should be deep enough to just cover the crayfish—approximately 4 to 5 centimeters. Crayfish do not survive deep-water conditions unless oxygen is supplied by an aerator.
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