Dissection in biology provides a hands-on education above and beyond reading a textbook. By seeing, touching and exploring different organs, muscles and tissues inside an animal and seeing how they work together allows you to really understand your own body and appreciate the amazing world around us. And it’s not hard – you can dissect a crayfish right at home using an inexpensive specimen with a dissection guide and simple dissection tools! Many doctors, surgeons and veterinarians report that their first fascination with the body started with a biology dissection class.

In today’s dissection, we’ll be looking at a crayfish. Crayfish are members of the phylum Arthropoda. There are many things that make crayfish interesting: they dwell at the bottom of streams, rivers, and ponds; they feed on just about anything that comes their way (that’s why they’re called freshwater scavengers); and they have many appendages that help them save energy.

Materials

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Procedure

  1. Observe the external anatomy of your crayfish. See if you can locate the following:
    1. Head
    2. Thorax
    3. Abdomen
    4. Cephalothorax (region where the head is fused to the thorax)
    5. Chelipeds (claws)
    6. Jointed walking legs
    7. Swimmerets (see if you can figure out whether your crayfish is
    8. male or female)
    9. Mouth
    10. Anus
    11. Antennae
    12. Telson
  2. Remove a section of the carapace
    1. Cut 1: Cut up the length of the crayfish--from the bottom edge of the cephalothorax to just below the eyes
      1. Keep your cut parallel to the table
    2. Cut 2: Cut straight down each end of your first cut
    3. Cut 3: Cut the length of each side of the abdomen using the same technique you used in cuts 1 and 2
    4. Remove the exoskeleton
  3. Look for the following organs:
    1. Gills (connected to the walking legs)
    2. Heart
    3. Esophagus
    4. Digestive gland
    5. Cardiac stomach
    6. Pyloric stomach
    7. Intestine
    8. Anus
    9. Green glands
    10. Nerve cord
    11. Gonads

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