Crazy Chromatophore Camouflage

Click to embiggen, clicky-poppy.

You probably know about animals that camouflage themselves. There's no shortage of them, and they come in all varieties and degrees of detail. At one end of the camouflage scale you've got things like lions and other animals that are just the same general colour as their environment.  It's fairly effective, particularly if the animal isn't moving.

Click to embiggen, clicky-poppy.

The next step up the camouflage scale, which may or may not be as effective depending on the particular situation, are animals with some sort of pattern to help hide them, usually it works by making the exact dimensions of the animal hard to notice.  This is an extremely common form of camouflage, being used by birds (some owls, bitterns, rock doves, etc), plenty of mammals (baby deer, tigers, etc), many fish (salmon, trout, etc), lots of reptiles (frogs, rattlesnakes, etc), a whole assortment of insects (moths, beetles, etc).  This is basically the principle that military camouflage is based upon.

Click to embiggen, clicky-poppy.
Actually two insects in the pic.

One step further up the ladder are animals that have evolved to look like something specific, such as sticks or dried leaves.  Their skin colours and textures match something specific, and often their body shape does as well.  This is most common amongst the 'lower lifeforms' such as insects, although it does crop up elsewhere.  Many seahorses have evolved to look exactly like a specific type of plant, for instance, and there's several species of frog that have evolved to have skin the same colour and texture as a moss that's common where they live.  Even when you're looking for these creatures, they're nearly impossible to spot.  Hell, even if there's a case of them at the zoo, I still have difficulty finding them.

There's one level up from them though, and it's active camouflage.  The best known example is the chameleon.   Most active camouflage is based on chromatophores, specialized cells either in the skin or just beneath it that either contain a pigment or that can produce one.  Generally they open or close to show or hide the pigment they contain.  Open, and you see it.  Closed and you don't.  They can come in all sorts of colours, depending on the species, and as a result the animals can be all sorts of colours.  Most chameleons go from green to either brown or black, but some also have yellow, blue and red chromatophores, so they can change to those colours as well.  But the chameleon, despite having a name synonymous with blending in, is hardly the master of hiding.  The indisputable kings of camouflage are the cephalopods.

Remember those giant optic lobes that we talked about?  Part of the reason their vision is so important is so that they can properly camouflage themselves.  And they do it very, very well.  In addition to having a lot of chromatophores (up to 20million of them), they can also change the texture of their skin.  They can go from pale white and smooth to red and spiky in an instant.  Where it can take a chameleon minutes to change from green to brown, an octopus can change its appearance almost as quick as you can blink.

Below, I'm going to post a bunch of videos (all under 4minutes) which go from least dramatic changes to most.  I suggest watching them in order, because they also go from most broadly informative to most specific as well.

 

 Cuttlefish and chromatophore info

Cuttlefish mating and colour displays, check out the rippling display pattern.  Awesome.

The mimic octopus, shows an octopus imitating several other different animals.

An absolutely brilliant example of octopus camouflage.  It's so good it looks faked.

Cephalopods: So strange they look like they're CG'd.

So there we go, the end of Unofficial Cephalopod week.

What have we learned? That octopuses have several redundant systems, including their blue-blood pumping hearts and their brains, that they can crawl into some frighteningly small places and that some artists quite like that idea, and that when they decide to take over the world, we'll never even see them coming.

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Sources:
All the YouTube videos above
Lion image taken from Mirror.co.uk
Bittern image taken from  Utah Conservation Data Center
Mantis and leaf insect image taken from What's That Bug.com
Wisegeek.com article on chromataphores
National Geographic article on chameleons