Cephalopods and their incredible color change

Cephalopods, more commonly known as squids, cuttlefish and octopuses are some really incredible and interesting animals. They are pretty smart, they are fast swimmers and they are well known for squirt ink into their environment, and disappear in a blink of an eye. If you have ever tried to catch one, then you would also know they are superb at getting away, even when they are locked in a cage, they can squeeze through all small spaces like between bars or holes that are several times smaller than themselves. The most impressing thing about them though, must be their use of colors and their incredible ability to alter their color in matter of seconds.

What makes cephalopods able to change color?

Their secret lies in some cells they have lying right under their outer skin layer. These are special cells called chromatophores. They are surrounded by layers of muscles that can constrict (temporary state) or expand (relaxed state), and within these cells are pigments. There are only one kind of pigment in each chromatophore, but different chromatophores can have different kinds of pigments. When the muscles constricts, they push pigments from the cell closer to the outer skin layer. More precisely, in constricted state, the cell will have a flattened disc-shape at the top (against the outer skin layer), where the pigments will occupy the space and the color gets more visible. If the muscles returns to relaxing state (expanded), the cell will shrink back to a small blob, and will retract from the outer skin layer. Cephalopods can decide which chromatophores they will constrict and expand, and this makes them capable of showing different colors and patterns (Harris 2001).

Why would a cephalopod want to change colors?

They have several reasons to change color. One is that they uses this to fit perfectly into the environment and be camouflaged well. If the environment changes, then so do they. They can have a broad range of different chromatophores, some have as many as five different ones (Douma 2008), which means they can create several different patterns and combinations, because they can decide exactly which colors they want to show at any time, and this make them capable of hiding or looking less conspicuous with all sorts of backgrounds(Meyer 2013).

Another reason for changing color can be if a predator approaches, then a cephalopod will expand chromatophores to create distinctive color patterns to warn a predator that they might be dangerous or bad for eating, just like other animals that also uses aposematism. They can also use different colors if they mimic something. Some of them are exceptional at mimicking other sea creatures, so with their ability to change color as well, they look even more convincing (Meyer 2013).

A third reason for color change can be communication. Several species have males that can change color to attract females or repel other males. Some might flash colors for a period of time, and this is thought to yield some kind of information that humans know little about (Meyer 2013).

What are pigments?

Pigments are different chemical components you can find in both living organisms and in inorganic matter. There are many different pigments, but what they all essentially do, is absorbing one or several wave lengths from the light spectre and reflect others. Different wave lengths that are reflected, are perceived as different colors.( see: Douma 2008)

Here I have a great video showing how cephalopods can change their colors and use it for different purposes.

  https://www.youtube.com/watch?v=aoCzZHcwKxI, viewed 27 May 2014

References:

Harris, T 2001, HowStuffWorks.com(Discovery communications), Atlanta, US,viewed  7 Mai 2014,<http://animals.howstuffworks.com/animal-facts/animal-camouflage2.htm >

Meyer, F 2013, How Octopuses and Squids Change Color, National Museum of Natural History, Washington DC, US, viewed 7 May 2014,

<http://ocean.si.edu/ocean-news/how-octopuses-and-squids-change-color >

Douma, M, curator, 2008, Cause of Color: Biological Pigments, Viewed 7 May 2014, <http://www.webexhibits.org/causesofcolor/7I.html >