f01u5p2 - Unit Five COAST/Blue Crabs Unit V Consortium of...

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Unit Five COAST/Blue Crabs Project Oceanography Fall 2001 70 Unit V Consortium of Oceanographic Activities for Students and Teachers-COAST Written by Harriet Perry On the cutting edge… The blue crab ( Callinectes sapidus ) supports a large commercial fishery and is also important to the ecology of coastal bays and estuaries. These crabs are abundant, environmentally tolerant animals that are available to the fishery year- round. Commercial fishing for blue crabs dates “back” to the late 1800s in both the Gulf of Mexico and the Chesapeake Bay. Issues facing the fishery include loss of critical nursery habitat, excessive numbers of fishermen and traps, and environmental pollution. Blue Crabs Lesson Objectives: Students will be able to do the following: Label correctly the internal and external anatomy of a blue crab Conduct a dissection of a blue crab, observing the internal organs Identify basic aspects of blue crab life history and current issues facing the blue crab fishery Key Concepts: crustacean, dissection, blue crab, commercial fishery, estuary, habitat What is a Blue Crab? More than 90 different kinds of crabs live in the Gulf of Mexico’s coastal waters. They are found in every type habitat from the saltiest water of the Gulf to the almost fresh water of the upper bays. The blue crab ( Callinectes sapidus ), favors brackish waters and is the most common, edible crab along the East and Gulf Coasts. It is also found on the Atlantic Coasts of Central and South America and has been seen in the coastal waters of France, Holland, and Denmark. Crabs are crustaceans . True crabs have five pairs of legs and belong to a group called decapods . In blue crabs, the first legs are modified as pinchers and the next three pairs are used as walking legs. In blue crabs, the fifth legs are modified into paddles or swimming legs. These legs are used for burrowing and for swimming rapidly. Other familiar crustaceans are shrimps, lobsters, crayfish, and barnacles.
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Unit Five COAST/Blue Crabs Project Oceanography Fall 2001 71 The back of the blue crab is dark or brownish green and is “drawn out” on each side into a long spine . When fully grown it may be more than seven inches wide. The abdomen and lower legs are white. The claws are various shades of blue, but the claw tips of the female are red. The sexes can be identified by the shape of the abdominal flap or apron. In the male it is shaped like an inverted T, but in the female it is broader and circular in shape as an adult and triangular when immature. As with other crustaceans, the blue crab must molt or shed its hard, outer shell to increase in size. In a complex process called ecdysis (molting or shedding) a new soft skeleton is formed beneath the old one. This stage is called the peeler . The
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This note was uploaded on 07/31/2011 for the course OCB 6050 taught by Professor Staff during the Spring '11 term at University of South Florida.

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f01u5p2 - Unit Five COAST/Blue Crabs Unit V Consortium of...

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