The External Anatomy of the Crayfish Virtual Lab

Go to Anatomy of a Crayfish Use the page to answer the questions and complete the lab

Prelab Questions:

1. Crayfish belong to the Kingdom __________________, the Phylum _________________________,
and the subphylum _________________________________________

2. List three characteristics that all arthropods share.

3. Name two other animals in the same phylum as a crayfish (related).

The Head:

Place the crayfish ventral side up so the mouthparts can be observed. (Check each box upon completion)

4. Locate the 1st, 2nd, and 3rd maxillipeds. These appendages are used for manipulating food. (The 3rd maxilliped is the largest and topmost one, the 2nd is underneath, and the 1st is underneath the 2nd) check box

5. Locate the mandible which lies underneath the maxillipeds. This structure should be hard and difficult to move. The mandible of arthropods opens differently than the jaws of humans. check box
Describe the difference. _______________________________________________________________

6. Locate the two large antennae and the smaller antennules that branch from the base. The antennae are sense organs (touch, taste, equilibrium) check box

7. Locate the eyes, which extend from two stalks called pedicles. check box

The Body & Appendages

8. The body of the crayfish consists of a fused head and thorax: the cephalothorax. The cephalothorax is covered by a thick armor called a carapace. Extending from the carapace is a pointy structure called the rostrum. Locate the cephalothorax and rostrum. check box

9. The abdomen of the crayfish is segmented and flexible. You can also see the swimmerets attached to the abdomen.check box
. Locate the swimmerets (appendages attached to each segment of the abdomen). Are the swimmerets jointed? ______ How many pairs of swimmerets are there? ______check box

10. Count the number of segments on the abdomen.How many segments are on the crayfish? _____

11. Locate the chelipeds (the claws). How many joints are visible on this appendage?_________ check box

12. Behind the cheliped are the walking legs. How many are visible?_____check box

13. The last segment of the abdomen (the 7th segment) is called the telson, and it is specialized for swimming. Locate the two uropods extend from either side of the telson. check box

14. Watch the video of the lobster, a relative of the crayfish. Describe how the lobster uses its legs and its telson to avoid predators: ___________________________________________________________________ check box

Determining the Sex of Your Crayfish

15. How can you tell the sex of a crayfish? _____________________________________________________ check box


16. Label the crayfish picture below. check box