Exploring Our Fluid Earth

Materials

• Fig. 3.71.1
• Fig. 3.71.2
• Fresh or defrosted squid
• Wax paper
• Newspapers
• Dissecting scissors or scalpel
• Blunt probe
• Microscope slide
• Dissecting microscope

Fig. 3.71.1. Diagram of external squid anatomy

Image by Byron Inouye

Fig. 3.71.2. Diagram of internal squid anatomy

Image by Byron Inouye

Procedures

1. Lay the squid dorsal side down on a piece of wax paper laid over some newspapers. Lay the squid with its head to the left and its siphon opening upward (Fig. 3.71.1).
    
2. Reach under the animal and remove the pen from the dorsal side by grasping it firmly with your fingers and pulling it free from the mantle.
    
3. Using a scalpel or dissecting scissors, cut the mantle from its anterior edge next to the siphon to its posterior tip. Do not cut into the internal organs.
    
4. Using a blunt probe, find the internal organs listed below (Fig. 3.71.2). Describe their functions. Draw and label the following organs:
   
   1. Caecum
   2. Intestine
   3. Pen
   4. Ink sac
   5. Heart
   6. Ovary and testis
   7. Gills
   8. Chromatophores
   9. Kidney
   10. Nidamental gland
        
5. Examine a single sucker from an arm.
   
   1. Cut off a 0.5 centimeter (cm) piece of the arm and place it on a glass slide.
   2. View it under the dissecting microscope.
   3. Draw a single sucker in your notebook.
       
6. Observe the chromatophores, small frecklelike spots on the outer layer of the mantle. Cut out or peel off a small piece of the skin that contains the spots. Observe at about 20x under a dissecting microscope. Stretch the skin, noting any apparent change of color. Record your observations.
    
7. Remove the beak.
   
   1. Cut out the arms from the head with a scalpel.
   2. Pull out the beak. Wash it and save it. Sketch it in your notebook.
   3. Remove the internal organs and wrap them in a plastic bag or newspaper. Give them to your teacher or save them for feeding aquarium organisms.
   4. Carefully wash the mantle, making sure it is very clean.