Crayfish- Virtual Dissection

a.) 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 (Miller and Harley, 1992; Snodgrass,1965). The digestive gland secretes digestive enzymes and aids in the absorption of the products of digestion (Pennak, 1989). http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

b.) 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 (Miller and Hurley, 1992; Snodgrass, 1965). http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

c.) Nervous System: The crayfish nervous system is composed of a ventral nerve cord fused with segmental ganglia, and the supresophageal and subesophageal ganglia (Miller and Harley, 1992). Giant neurons in the ventral nerve cord function in escape responses (Bliss, 1990). The supraesophageal and subesophageal ganglia control the head appendages in response to sesory input recieved from receptors (Miller and Harley, 1992). http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

d.) Excretory System: The excretory organs are 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 (Miller and Harley, 1992). Ammonia is also excreted across the gill surfaces and by diffusion across thin parts of the exoskeleton (Snodgrass, 1965) http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

e.) Reproductive System: Crayfish have separate male and female sexes (dioecious) and the gonads are located in the dorsal portion of the thorax (Miller and Harley, 1992). 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. http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

f.) Integumentary System: This crustacean has a hard exoskeleton that protects and supports the body. The crayfish has 8 jointed walking legs, a segmented body, 2 pairs of sensory antennae, and compound eyes. It has 2 large pincers or claws called chelipeds. If a crayfish loses a leg, the leg will regenerate (regrow). The head and thorax are fused, forming the cephalothorax. Using gills, a crayfish breathes oxygen that is dissolved in water. Juvenile crawfish are light tan, but adults are deep red. http://www.enchantedlearning.com/subjects/invertebrates/crustacean/Crayfishprintout.shtml

g.) Body Plan: The body of the crayfish is divided into two regions: the cephalothorax, which has sensory, feeding, and locomotor functions; and the abdomen, which has locomotor and visceral functions (Miller and Harley, 1992) http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

Description of its unique habitat, diet and what distinguishes it as a mollusk, echinoderm, or arthropod.--> Crayfish live in streams, rivers, swamps, ponds, and other freshwater habitats. Most crayfish are strictly aquatic but some live in semi-aquatic environments. The semi-aquatic crayfish burrow into the soil to get to water (so that they can breathe). Crayfish are omnivores; they eat plants, animals, and decaying organisms. They are nocturnal (most active at night) and eat fish, shrimp, water plants, worms, insects, snails, and plankton. Larval crayfish are very tiny; they eat plankton. Their color depends on diet. As a crayfish grows, it often molts (loses its old shell and grows a new one). It eats the old shell. http://www.enchantedlearning.com/subjects