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October 3, 2005

Creepy Creature Camouflage

An animal's ability to survive and thrive, and therefore to reproduce, is key to the success of a species. Any advantage gained only serve to further this goal - whether by mutation, accident or purpose. A species adapts gradually, through the process known as natural selection. In the wild, an individual animal with any advantage lives longer. Consequently, the animal has the opportunity to reproduce more animals like it - passing the advantage to its offspring. Two of the most common and interesting adaptations that animals use to help them eat and keep them being eaten are camouflage and mimicry.

NATURAL CAMOUFLAGE

Blending In

Animals, and plants for that matter, often try to make themselves look more like the landscape in which they live. They do this to avoid detection - sometimes because they want to make it harder for predators to see them, and sometimes because they don't want prey to know they're there to ambush them.

Leafy sea dragons look more like the drifting kelp that they live in than many of their sea-horse cousins. They've even adapted to move so slowly, they appear to drift as opposed to swim. Only by watching them very closely will you notice any locomotion or eye movement.

The Great White Shark is another example of creature camouflage. I know, I can't seem to go more than five posts without mentioning this shark but hey, it's my favorite animal. The great white is not a big white fish, it's actually got a fairly sophisticated coloring to help it ambush predators - from above or below. Only it's underbelly is white, making it difficult to see if you look up at it. It's back and fins are actually a grey blue color, making it difficult to see it below you. This makes perfect ambush coloring for the world's largest predatory fish.

One thing that is interesting is that while mutations happen (so you'll might encounter a random characteristic), nature doesn't usually support adaptations that don't serve a purpose. In other words, every feature generally has a purpose; mutations that don't give the animal some advantage will not stick around in a healthy population of the species.

An animal will not develop any camouflage that does not help it survive, so not all animals blend in with their environment the same way. For example, there's no point in an animal replicating the color of its surroundings if its main predator is color-blind.

More At: How Animal Camouflage Works

Also, it's important to remember that camouflage doesn't have to be in the form of visual physical characteristics. Some animals, especially aquatic ones, also mask their scent from predators.

Now You See Me, Now You Don't!

Some animals have the ability to change their appearance to suit the environment and blend in better. Sometimes this change happens seasonally. For example, a rabbit (or a fox, for that matter) might have brown fur in the summer and white fur in winter. Other animals, like the anole lizard, can change their coloring on the fly to blend in with a leaf or bark color, unlike chameleons, which change their color based on mood.

Disruptive Appearances
Some creatures use coloring to protect themselves in other interesting ways... Some animals change their appearance to make them look bigger, by puffing out their chests or fluffing their fur. Other animals take this further by changing their coloring to confuse predators and prey. The disruptive coloring mechanism can often explain some of the oddest animal coloring phenomena in nature.

In Africa, one of the laws of nature is safety in numbers. A lone zebra may seem out of place against the earthy colors of the savannah, but the animal's striped coloring provides an excellent example of disruptive appearance.

To a lion, a herd of zebras doesn't look like a whole bunch of individual animals, but more like a big, striped mass. The vertical stripes all seem to run together, making it hard for a lion to stalk and attack one specific zebra. The stripes may also help a single zebra hide in areas of tall grass. Since lions are colorblind, it doesn't matter that the zebra and surrounding environment are completely different colors.

More At: How Stuff Works: The Element of Disguise and How do a zebra's stripes act as camouflage?

MIMICRY

Any animal that has evolved to resemble another successful species in order to fool predators or lure prey is called a mimic and you'll often see examples of mimicry - especially in insects. There are four basic kinds of mimicry.

Me, Myself And I

The first type of mimicry is probably the weirdest. When an animal mimics some part of it's own body, it's called automimicry. I've seen this most often in reptiles that seem to have a head at both ends. A bird might attack a poisonous snake or lizard, but if it appears to have heads at both ends, it's unclear which end is "safe" and also which direction the prey is likely to run - this confuses the bird and it's likely to try for easier prey elsewhere.

If Only Looks Could Kill

Batesian mimics take on the look of a species with an attribute that discourages predation but does not actually have that attribute themselves. In this instance, a yummy-tasting frog may take on the colorings of a poisonous frog in order to deter predators, but it's still not poisonous itself. Another example of Batesian mimicry is the Aegeria moth, which resembles a yellowjacket wasp, but has no stinger. Some butterflies have a marking on each wing that looks like the eye of a large animal, and there's even a caterpillar that looks like a snake!

More Than Skin Deep

Müllerian mimics resemble the successful species but also come to share the anti-predation attribute. In this way, both species benefit from the advertisement of their unpalatability to predators with less loss of life to a single species. A good example of Müllerian mimicry is the honeybee, because it shares a similar appearance with the yellowjacket wasp, and they both can sting.

A Wolf In Sheep's Clothing

Lastly, there are aggressive mimics. Like the Big Bad Wolf when he dressed up like Little Red Riding Hood's grandma, aggressive mimics resemble something harmless in order to lure unsuspecting prey. Malaysian preying mantids resemble flowers, which lure bees to be eaten. There's also the ultimate femme fatale, the Photuris firefly female will mimic the blinking signal of other species of firefly, luring the unsuspecting males to be eaten. If you've seen the movie Master & Commander, you'll know about the walking stick, an insect that looks like an ordinary twig.

You can find some great pictures of animals known for their camo and mimicry adaptations at Wayne's Word: Photos Of Ecological Adaptations and The Wild Ones: Insect Camouflage and Mimicry.

Photographer Art Wolfe has also published a new book entitled Vanishing Act in which he disregards the standard wildlife photography conventions of capturing dramatic action and instead shows us how they normally appear in nature - trying to blend in. You can see some of his pictures in Smithsonian Magazine: Hiding in Plain Sight.

Posted by sorsha at October 3, 2005 12:35 PM