It is cephalopod week on NPR (one of my favorite radio stations) and I wanted to share some fun facts about these amazing creatures. If you don’t know, cephalopods are a class of marine animals under the phylum Mollusca (a.k.a. mollusks) and are defined by their bilateral symmetry and tentacles. The most common cephalopods are squids, octopus, and natalists.
My personal favorite is the octopus. There are 300 recognizable species that are identified by their soft-bodies, 8 arms, and a beak. The beak is the only hard, bone-like structure that an octopus has and because of this, they can squeeze through anything that their beak can fit through. This is why you can see videos of them making incredible escapes off boats or out of nets. Also, octopi are color blind. Now, I know just saying that they cannot see color is not surprising. Yet, when you add in the fact that octopi change colors and texture to match their environment perfectly, that makes it pretty interesting (I think). So, they can figure out what colors to change into with just shades of grey, and on top of that, most octopi live on or near coral reefs that contain dozens of bright and vibrant colors. I don’t know about y’all, but I think that is amazing and speaks to their intelligence. That is not the only thing that shows their intelligence, the fact that they can learn through observation also highlights how smart they are.
Learning through observation used to be thought of as only an invertebrate thing, and real smart invertebrates at that. However, the discovery of octopi being able to learn through observation by researchers Fiorito and Scotto (1992) changed all that. A more recent experiment was done in Italy that better highlights this amazing ability. Stazione zoological, in Naples, did a puzzle box experiment. They would capture a wild octopus from the harbor of Naples and put her into a tank with a puzzle box containing a tasty looking crab. This box had two possible solutions, but with no hints or encouragement, the wild octopus gives up after a few minutes of trying. After she gives up, they take her to a different tank that shares a wall with a captive octopus, who gets presented with the same box. The captive octopus, who has seen this box hundreds of times, quickly unlocks the box and gets her tasty treat. After watching her neighbor, the wild octopus gets another chance at the box. This time she gets it open! “Learning through observation” is seen in animals like humans and chimps, and now octopi.
The next cephalopod I want to talk briefly about is the cuttlefish. They are similar to the octopus in that they can also change colors. However, the cuttlefish use it for more than one purpose. Instead of using it just for camouflage to hunt or hide, they use it for communication. They change the color and texture of their skin to express emotion or threats. Studies done by Amber Thomas (2016) and Anna C. Crook (2002) show that cuttlefish have 32 to 75 distinct color patterns, 8 to 15 positions, and 6 to 7 skin textures in order to communicate. That means the cuttlefish has hundreds of potential messages that they are able to pass to one another. But, that is not the only unique aspect about the cuttlefish, they also have a thing called the cuttlebone that no other mollusk or fish has. The cuttlebone is a porous aragonite (calcium carbonate) structure in the back of the cuttlefish. It uses this to control its buoyancy by changing the gas-to-liquid ratio in the chamber. Because this adaptation is a hard aragonite structure, unlike the typical swimming bladder that most fish have, the cuttlebone will explode at 200-600 meters. This restricts the habitat of the cuttlefish to shallower water, typically near the continental shelf. Those are some of the reasons that I believe cuttlefish are so interesting.
I told y’all about two of my favorite cephalopods and some fun facts about them. I truly believe that cephalopods are some of the most interesting and intelligent creatures under the sea. I hope you enjoyed and learned something new about these amazing creatures.
Keep on learning and Enviroventing!