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.

1. Measure the length of your crayfish in cm from the rostrum to the telson and record in Table 1.
2. Draw the external dorsal view of your crayfish into Figure 1. 
3. Label the following: eye stalk, antennae, thorax, abdomen, cheliped.
4. Look at the ventral side of the crayfish.  Using your computer, see if you can determine the sex of your crayfish. Record in Table 1.
5. Count the number of walking legs and record in Table 1.
6. On the ventral side, locate and sketch (Figure 2) the following: dorsal,anterior, posterior, (cephalo)thorax, abdomen, cheliped, walking legs, swimmerets, uropods
7. Carefully remove the carapace to expose the gills and interior cavity.
8. Make an incision along the dorsal side of the abdomen.  Be careful not to cut too deeply.
9. Make a sketch of the internal view in Figure 3.  Label the following: gills, stomach, intestine, heart, digestive gland, green gland
11. 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!

Figure 3: Internal Dorsal Anatomy of the crayfish- be sure to label all parts!

Table 1: Crayfish Information Table
 

Length of Crayfish in cm
Sex of crayfish
# of Abdomen Segments
Length of Right Cheliped in cm
Number of Walking Legs

 

For pictures of the dissected crayfish visit this wonderful site: Crayfish Review

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