Crayfish Dissection
BY WILLIAM FOX
Objectives:
- to observe the external and internal anatomy of a crayfish.
- to determine the sex of a crayfish using external anatomy.
- to collect statistical data on crayfish length and cheliped length.
Procedure:
- Measure the length of your crayfish in cm from the rostrum to the telson and record in Table 1.
- Draw the external dorsal view of your crayfish.
- Label the following: dorsal,anterior, posterior,head, antennae, thorax, abdomen, right cheliped.
- Look at the ventral side of the crayfish. Using your handout, see if you can determine the sex of your crayfish. Record in Table 1.
- On the ventral side, locate and sketch (Figure 2) the following: dorsal,anterior, posterior, (cephalo)thorax, abdomen, right cheliped, walking legs, swimmerets, uropods
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- Count the number of walking legs and record in Table 1.
- Make an incision along the dorsal side of the abdomen. Be careful not to cut too deeply.
- See if you can find the intestine and muscles. Label in Figure 3.
Data: (leave a 1/2 page for each figure and table)
Figure 1: External Dorsal Anatomy of the Crayfish- be sure to label all parts!
Figure 2: External Ventral Anatomy of the crayfish- be sure to label all parts!
Table 1: Crayfish Information Table
Length of Crayfish in cm |
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Sex of crayfish |
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# of Abdomen Segments |
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Length of Right Cheliped in cm |
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Number of Walking Legs |
| Table 2: Summary Data Table of Crayfish Length and Cheliped length (cm)
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Crayfish Length in cm |
Cheliped Length in cm |
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Analysis:
- What sex was your crayfish? How did you know?
- Was there a pattern to how many tail segments the crayfish have?
- What length in cm was the longest/shortest crayfish? What about the median?
- Mathematically determine if there is a relationship between cheliped length and crayfish length.
Conclusion: 2-3 sentences on what you learned
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