Excretory: it is also called the antennal glands because they are located at the base of the second antenna. They exrete the waste products of blood filtration; ammonia is the primary waste product Ammonia is also excreted across the gill surfaces and by diffusion across thin parts of the exoskeleton

Circulatory System: The circlatory system of the crayfish is centred around a muscular heart with dorsal, anterior, and posterior arteries leading away from it .Branches of these vessels empty into the sinuses of the hemocoel (the large tissue spaces containing blood). The ventral sinus collects the blood, the blood travels through the gills, and then returns to the pericardial sinus surrounding ther heart .

Nervous System: The crayfish nervous system is composed of a ventral nerve cord fused with segmental ganglia, and the supresophageal and subesophageal ganglia. Giant neurons in the ventral nerve cord function in escape responses . The supraesophageal and subesophageal ganglia control the head appendages in response to sesory input recieved from receptors .

Reproductive system: Crayfish have separate male and female sexes (dioecious) and the gonads are located in the dorsal portion of the thorax. Mating occurs just after the female has molted, usually in the spring. The male deposits sperm near the openings of the female gonoducts (at the base of the 3rd periopods) and uses the two modified pleopods to guide the sperm into the female sperm receptacle.

Digestive System: The digestive tract consists of the foregut, which includes an enlarged stomach, part of which is specialized for grinding; the midgut, which extends from the foregut; and the hindgut, which leads to the anus and functions in water and salt regulation .The digestive gland secretes digestive enzymes and aids in the absorption of the products of digestion

Integumentary system: crayfish has hard exoskeleton that covers its body. its body is divided into two main parts, the cephalothorax and the abdomen. The cephalothorax consists of the cephalic (or head) region and the thoracic region. The part of the exoskeleton that covers the cephalothorax is called the carapace. The abdomen is located behind the cephalothorax and consists of six clearly divided segments. The cephalothorax consists of 13 segments. Each segment of both the cephalothorax and the abdomen contains a pair of appendages. The head (or cephalic) region has five pairs of appendages. The antennules are organs of balance, touch, and taste. Long antennae are organs for touch, taste, and smell. 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. Of the eight pairs of appendages on the cephalothorax, the first three are maxillipeds, which hold food during eating. The chelipeds are the large claws that the crayfish uses for defense and to capture prey. Each of the four remaining segments contains a pair of walking legs. In the abdomen, the first five segments each have a pair of swimmerets, which create water currents and function in reproduction. The sixth segment contains a modified pair of uropods. In the middle of the uropods is a structure called the telson, which bears the anus. The uropod and telson together make up the tail fan. The crayfish moves backward by forcing water forward with its tail fan.

Body plan: A crayfish has a lot of body parts. The most important parts of a crayfishes body are the carapace, tail, legs, heart, claws, brain, egg pores, long antenna, short antenna, stomach, digestive gland, bladder,intestines, modified swimmerets, and swimmerets.

Habitat and diet: A crayfish`s habitat is a lake near shallow water under rocks. The pond or lake is were you would probably find one. Crayfish eat many things. In there natural habitat they will eat fish, earth worms, tadpoles, snails, plants, and small fish. To distinguishes crayfish, you have to look at its body just as legs, tail, out surface of the body, claws and its activities.

The pictures are find in:

1. http://images.google.com/images

2.http://sps.k12.ar.us/massengale/crayfish_dissection.htm