One of the many popular EV kits used for school services is “Squid Dissection.” For those of you who shy away from presenting this kit or have a hard time getting past the usual fifth graders’ reactions of “yuck” and nervous giggles, I have the perfect book for you: SQUID EMPIRE: The Rise and Fall of the Cephalopods, by Danna Staaf.
This is a very readable science book that covers the 500 million years of cephalopods adapting and evolving on Earth (longer than dinosaurs, with fossil records going back 230 million years). Thankfully the text of the book is only 200 pages.
I took lots of notes, much of which is beyond what we can cover in the classroom, but was pleased just recently to make use of my new knowledge. I had students go a step beyond the excitement of pulling out the squid’s beak — by also examining it’s brain!
Paraphrasing some interesting tidbits I learned —
*The brain is in three parts: one optic lobe behind the left eye, another optic lobe behind the right eye, and between them a strangely shaped doughnut of nervous tissue. Through the doughnut hole runs the squid’s esophagus. This is the most direct route from the mouth into the mantle, where the stomach and other organs lie, but as you might imagine, swallowing through your brain can be risky. The squid must ensure that each bite is small enough to pass and devoid of sharp bones.
*Imagine that the squid sees a fish. In a few hundredths of a second, the two tentacles shoot out. Their flattened clubs suction onto the fish and yank it back toward the squid’s head. Now the 8 sucker-lined arms embrace the prey, while a hawk like beak severs its spinal cord. The squid proceeds to take one bite at a time, swallowing with the help of a rasping tongue called a radula and hoping not to skewer its brain.
*Cephalopods began as shelled ocean-bottom dwellers and adapted and evolved as the environment and their predators changed. Squid ancestors filled their shells with gas and floated up through the water. They were slow swimmers, but they had no need for speed at that time. Then fish, with shell-breaking jaws became predators.
Today, as Dana Staaf says, “Jet propulsion is extremely rare in nature, and among those animals that use it, squid are the fastest by far.”
Fascinating history, and a great read.
Review by Nancy Mayo, School Programs EV