Each year, we celebrate Cephalopod Awareness Day in honor of the important role that cephalopods (which include squids, cuttlefish, nautiluses, and octopuses) play in the marine ecosystem. October 8 might seem like a random date for this important day, but in fact it’s based on the number of appendages that cephalopods have: squids and cuttlefish have 10 appendages, while octopuses get by just fine with 8. Get it? 10-8, or 8-10, depending on how you form your dates.
Did you know that the name “cephalopod” literally means “head and feet”? Of course, cephalopods are aptly named not just because their bodies resemble a large head set upon 8 or 10 “feet” but also because cephalopods are the brainiest of all invertebrates. In fact, with their large brain-to-body mass ratios, cephalopods are considered more intelligent than most species of fish and reptile. Many scientists have taken this perspective so far as to declare some cephalopods self-aware, that is, possessing the capacity to exhibit intentional behaviors and the ability to undertake complex planning.
Here’s a bit of food for thought regarding the complex, unique nervous system of cephalopods that enables their high degree of intelligence. We humans tend to think of certain feats of engineering as human advances. For example, humans developed the ability to maneuver during aerial flight, harnessed the physics of buoyancy and Newtonian fluids to dive to the murky depths of the ocean, engineered sophisticated jet propulsion technologies, and created electricity to bring light to darkness. Right?
Wrong! Brainy cephalopods accomplished all of these feats long, long before humans did – and without the “higher intelligence” of the human brain!
From the perspective of intelligence (and hence self-awareness), here are a few more amazing facts about the nervous systems of cephalopods, which are generally regarded as being the most intelligent of all cephalopods.
- Amazing Fact #1. Though fundamentally based on the molluscan ganglial design, the cephalopod nervous system has a highly complex organization and structure compared to other mollusks, like clams. In fact, the cephalopod’s nervous system is recognized as the most complex of all invertebrates.
- Amazing Fact #2. Cephalopods possess the largest brains relative to their body masses of all invertebrates and most species of fish and reptile.
- Amazing Fact #3. The nerve cells in the cephalopod eye attach to the back of the eye’s photoreceptors, allowing the entire retinal surface to be used for image acquisition. In contrast, the vertebrate eye possesses a “blind spot” because the nerves are attached to the front of the photoreceptors and hence must penetrate through the retina to exit the eye via a large nerve bundle (the optic nerve).
These examples begin to shed light on why cephalopods possess such an amazing capacity to learn and solve problems, as well as why scientists find cephalopods so fascinating. Most importantly, we hope that on this day of cephalopod awareness, you’ve developed a newfound appreciation for the self-awareness (and intelligence!) of the amazing cephalopod.
And finally, what would any post on cephalopod intelligence be without a few videos demonstrating the awesome intelligence and problem-solving skills of the octopus!
- This octopus was filmed collecting and carrying coconut shells for protection, demonstrating tool use.
- An octopus at the Sea Star Aquarium in Germany made headlines in 2008 for repeatedly squirting water at a bright light fixture above its tank until the electrical system short-circuited (the staff eventually changed the arrangement).
- If you’ve ever struggled to open a jar, watch this octopus tackle the task with ease – from inside!
- This octopus learns a complex task by watching another octopus (even humans can’t always do this!).
by Liz Boatman
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