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Crayfish Disection

Biology A Disection

Cheyenne Ferris

on 22 January 2013

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Transcript of Crayfish Disection

Muscular Crayfish use strong muscle in their walking legs and the thorax to move. Crayfish have a hard exoskelaton fully cephalizated. The hard outer skeletan is like our skin. has claws instead of nails. Nervous The crayfish nervous system is composed of a ventral nerve cord. Giant neurons in the ventral nerve cord function in escape responses.The "brain" is a mass of nerve ganglion. Two nerves lead from the brain, around the exophagus, and combine to form the ventral nerve cord which runs to the end of the abdomen.
The crayfish has a brain like a human it has a ventral nerve cord which acts like our spine. Reproductive Crayfish have separate male and female sexes and the gonads are located in the dorsal portion of the thorax. Mating occurs 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.
Like humans crayfish have two seperate sexes and need sperm to fertilize an egg.
Unlike humans crayfish female produce 100 to 600 eggs. Respitory Researcher: Cheyenne
Dissector: Jenna and
Harley Crayfish Dissection
Biology A Domian: Eukarya
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decopda
Family: Astacoidea Integumentary Skeletal CARAPACE = single tough covering over cephalothorax (saddle);
ROSTRUM = “visor” protects eyes
MOLTING = periodic shedding of exoskeleton to allow growth; controlled by hormones
Flat paddle like tail for propulsion made up of TELSON (center part) & UROPODS (side sections)
SWIMMERETS create water currents and help in reproduction
(transfer sperm in males; carry developing embryos in females)
CHELIPEDS (pinchers) for capturing food and defense 2 main body regions: CEPHALOTHORAX & ABDOMEN Exoskeleton made of chitin, proteins, and lipids in some arthropods the shell can be hard
DECAPODS: 4 pair of WALKING LEGS for locomotion; plus CHELIPEDS (Pinchers)
TELSON/UROPODS can help crayfish swim backwards (tail flips) Crayfish Symmetry Cephalization Digestive System Coelom Jointed Appendages Vertebrae bilateral developed incomplete present present absent Reflection Questions Animal Characteristics The muscular system of crayfish includes powerful abdominal muscles that make it possible to swim backward rapidly and muscles in other parts of the body, such as in the pincers, walking legs, mandibles, and stomach.
Like humans it has strong hands (pincers and mandibles). They also have abs and strong legs (walking legs). The crayfish has no veins. Two arteries leave the heart, the abdominal aorta (toward the posterior) and the anterior dorsal aorta (toward the anterior). Blood flows from the dorsal arteries to capillaries and then into tissue spaces called sinuses which function as veins. The body of the crayfish is covered by a two-part exoskeleton made of chitin. Chitin contains a high percentage of calcium, similar to human fingernails.

A crayfish has an open circulatory system while humans have a closed circulatory system. "Closed" means that we have true blood vessels that carry blood to and from the heart. "Open" means that the organs are simply bathed in blood that freely circulates around the body. Sometimes the heart can move the "blood" by creating pressure waves in the fluid.
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