Cephalopods are a class of animals whose earliest fossils date back to the late Cambrian period, and dominated the oceans during the Ordovician. Modern cephalopods come in two sub classes:
- Coleoidea (who have mostly or completely lost their shells), which includes octopuses, squid, and cuttlefish.
- Nautiloidea (which still have a distinct shell) represented by Nautilus and Allonautilus.
And while I may be partial as a marine invertebrate biologist, cephalopods are some of the coolest animals on the planet. I spent a decade of my life working with Enteroctopus dofleini, the Giant Pacific Octopus.
Cephalopods have captured the imagination of millions throughout human history.
With their boneless, otherworldly bodies and large, complex eyes, it’s almost impossible for them not to. Octopus have eight arms, each equipped with 260 suckers that can taste as well as manipulate anything they touch. Their skin is covered in chromatophores, cells that allow the animal to change color. Their blood is blue and they have three hearts. The only hard part of their body is their beak, which looks very much like a parrot beak. Their brains are large compared to their nearest relatives and octopuses have eight “sub-brains”, one for each arm. Dr. David Scheel of Alaska Pacific University even poses that octopus may dream.
(The full documentary is available on Amazon HERE and is really neat).
While cephalopod bodies are very complex for a mere mollusk, they are very easy to dissect. The dissection can be done with child-safe scissors! Here follows the step-by-step instructions on how to perform a squid dissection on a Loligo opalescence (market squid), which are readily available frozen at the supermarket (if you cannot find them in your regular grocer, I have found them at Walmart and Asian grocers before). I have done squid dissections with kids from 1st grade to high school.
Squid Dissection.
Tools you need:
- cutting board
- scissors
- toothpick
- intact market squid specimen
Step 1. Start by looking over these squid anatomy sheets to see what you’ll be looking for during your dissection. Locate and observe all the external body parts: arms, feeding tentacles, eyes, siphon, mantle, fins.
Step 2. Locate and extract the gladius (pen) by pushing the skin on the mantle back gently and pulling the gladius out.
Step 3. Locate and extract the beak by applying gentle pressure behind beak and pulling it out.
Step 4. Use scissors to make a vertical cut straight down the middle of the mantle.
Step 5. Splay open the mantle and locate internal organs. Use toothpick to point out organs and move them as needed. See if you can locate gills, hearts, liver, digestive tract, ink sac and reproductive organs. See if you can identify male and female squid. When all organs have been found, use the toothpick to open the ink sac and watch ink spill out.
Step 6. Use scissors to make a small cut in the eyeball. Extract the lens by gently squeezing the eye. The lens will look like a clear, plastic ball.
You have now succesfully dissected a squid!
