Wild Fact #957 – A Bone to Pick with this "Fish" – Cuttlefish
Well, I hope everyone is having a great week so far. Today’s Wild Fact is going to be confusing because it is about a fish that isn’t actually a fish. That’s right, the cuttlefish is not actually a fish. It is a mollusk, so similar to an octopus or a slug. I know it is mean of me to try and trick you but I am not the one who named this fish…errr, I mean mollusk.
If you can remember the mimic octopus fact (if not you can check it out here) you will know that these mollusks’ were able to change colour and shape. Well, the cuttlefish is also able to change it’s colour and even the texture of its skin. Again this is used as camoflage to protect themselves from predators. As well, they will use flashes of colour to communicate with other cuttlefish in the area.
If any of you own a budgie then you may be familiar with the term “cuttlebone” which is used to provide calcium for the little birds. Tweety may love it but this cuttlebone has a much greater purpose when it is inside the living cuttlefish. The cuttlebone allows the cuttlefish to maintain buoyancy. This bone is unique to cuttlefish and varies in size and shape among various species. Although, I keep calling it a bone, it is mostly composed of aragonite which is similar to the endoskeleton of coral. The interesting part of the cuttlebone is the fact that it is a chambered gas-filled shell. Cuttlefish are able to regulate their buoyancy by changing the gas to liquid ratio in the cuttlebone. If humans had bones like this then we would never have to worry about wearing a life jacket. We would just need to increase the level of gas in the “cuttlebone” to make sure we stay floating.
Cuttlefish Fast Fact: Cuttlefish have some of the most developed eyes in the animal kingdom. Yes, an animal more closely related to a slug then to a human have some of the most developed eyes. Although, they can’t use their eyes to see colour they are polarized which helps them see contrast in the water column.
October 21st, 2009 at 1:47 PM
In the picture you posted, it looks like some of the colouring is neon. Is this just the way the picture appears or do they have some pigment in their skin that give it that “glow” effect. Your post are great, never fail to amaze me.
October 23rd, 2009 at 4:43 PM
Good eye! The glow that you are seeing is caused by specialized pigment cells called leucophores and iridophores. These cells give it that reflective colouring which they use to attract prey and communicate with other cuttlefish.
Thanks for the great question and the nice compliment.