crayfish essays

crayfish essays Crayfish are in the phylum Arthropod, and in the subphylum Crustacea. Arthropods have jointed appendages, segmented bodies, an exoskeleton, and a ventral nervous system. Arthropods have bilateral symmetry, and consist of 90% of the animal population ranging from spiders, to insects, to scorpions, to crayfish. Arthropods generally grow by molting their exoskeletons in a process called ecdysis. Movement of appendages is controlled primarily by a complex muscular system. There are 4 lines of evolution from arthropods: trilobite, crustacea, chelicerta, and uniramia. Crustacea includes approximately 30,000 species ofthis subphylum. Most are aquatic; of these, the majority are marine but some are found in fresh water. Members of the Subphylum include lobsters, crabs, crayfish, shrimp, copepods, barnacles, and several other groups of organisms. All have two pairs of antennae, a pair of mandibles, a pair of compound eyes, and a pair of appendages on each body segment. Crustacea have har d exoskeletons containing calcium carbonate, and are smaller animals. Some examples are barnacles, sow bugs, or isopods. Crayfish have bodies separated into 2 sections-the cephalothorax, and the abdomen. Crayfish have and open circulatory system, and the heart pumps to 7 large vessels with a central nervous system. They live in freshwater environments, such as a pond, stream, or marsh. They are nocturnal, and are most active at night. Crayfish are considered scavengers, and eat insects, small fish, and plants. In this lab, they ate green beans, carrots, and for protein chicken. Their gills must be kept moist, but can stay our of water for short periods of time. Their social behavior is not classified as party animals. The most aggressive crayfish is usually the dominant one, who receives the most desirable territory. Aggression is natural behavior in crayfish either directed at each other or anything that resembles a threat. The obj...