Megan Williamson period: 3 4/29/13 Objectives: The purpose of this lab was to study and observe the organs in a crayfish and be able to name them.
Introduction: Crayfish belong to the kingdom animilia, phylum arthropod and class crustaceans. The body is divided into three parts, the body, the head, thorax, and abdomen. The head and thorax are apart of a segment called cephalothoraxes, which is covered by the carapace made of chitin. The exoskeleton covers the outer body of the ventral side of the abdomen called swimmerets that help the crayfish with swimming. The first pair of appendages is called chelipeds they have huge claws that are used to get food and protection. The other four are walking legs. The crayfish have pairs of legs located on the thorax region. Antennae’s are found on the head of the crayfish that are used for taste and touch. There is a pair of mandibles located behind the antennae. Crayfish have bilateral symmetry, balance of the body parts on each side of the crayfish. Gills are attached to walking legs that are feathered and help them breathe. Crayfishes have an open circulatory system. The stomach is large two-chambered sack. The yellow glands are on each side of the stomach. An intestine is joined to the stomach and goes along the abdomen to the anus. The ventral nerve cord runs vertically down the body. The crayfish brain is behind the esophagus interior dorsal side.
Materials: goggles, gloves, Lab apron, zip lock bag, dissecting tray, scissors, forceps, probe, and preserved crayfish
1. Put on safety goggles, gloves, and lab apron
2. Place the crayfish on its dorsal side in the dissection tray locate the cephalothoraxes, abdomen, carapace, cervical groove, head, thoracic region, prominent suture, and individual segments of the abdomen. 3. Place required parts asked for on the crayfish appendage table. 4. Locate the five pairs...