I.) External Anatomy
1. Place the preserved crayfish in a dissecting tray.
2. Note that the body of the crayfish is divided into three parts, the head, the cephalothorax and the abdomen.
3. Head - Identify the compound eyes on the rostrum portion of the head.
4. Cephalothorax - Find the Carapace, the covering of the cephalothorax region.
5. Note the larger antennae and smaller antennules protruding from the rostrum.
6. On the ventral side, locate the mouth with the mandibles, or true jaws. The mandibles tear the food, and the other appendages detect and hold food during feeding.
7. There are five pairs of walking legs connected ventrally to the carapace region. The first walking leg has enlarged pincers called chelipeds, and is used to manipulate objects and capture and crush food.
8. Abdomen - This section is a segmented tail. On the ventral
side there are numerous swimmerets. The first pair is modified for
the transfer of sperm in those that are ready to mate. Identify the
uropod and the telson at the posterior end of the abdomen.
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