Bright on the bottom and dark on top – A Technique of Deception

[gusp]

Thanks for reading. Recently I saw a report on German TV comparing animals that were dark on top and bright on the bottom (insects, mammals etc.). I joined in rather late and didn't see most of the documentary.

The theory was, that most animals, including humans, automatically assume that the bright side of an object is on top and the dark side on the bottom (due to the sun light coming from above). By reversing this order, potential prey can fool or irritate predators, making it difficult to catch them. As with any of such features, they prey sooner or later adapts, but the phenomenon is so widespread, that it might still bring a big advantage.

One example I remember were gazelles, that have a bright stomach. They also showed a caterpillar that confused scientists, because it was dark in the stomach area and bright on its "back". But then they found out the caterpillar has an unusual walk and bends over backwards, basically walks upside down, so it made sence.

Anyway, do you happen to know what show this was (I'm assuming it was a British or American production) or what the name of that caterpillar is? Is there another place I should ask this question? Thanks a lot!

Also feel free to talk about the topic in general or name other examples.

[freeztar]

Interesting. Sounds like a good program.

What would be really neat is to find an example of an animal that uses this form of camouflage in conjunction with colors based on mate selection. I wonder if there even is an example of that.

[gusp]

It's called countershading.

[gusp]

This picture was taken by Abbott Thayer who was an artist and a pioneer of camouflage. Apparently there are two ducks on this image, one is counter shaded. It seems to work so well that I can't see the right one at all. If anyone can see it. please draw around the contours and reupload it (for example on pixentral.com), please.

http://upload.wikimedia.org/wikipedi...tershading.jpg

Thanks!

[freeztar]

I can't see it either.

It makes me think of hunting deer. You have to wear some camouflage, but it needn't be military grade. A simple plaid shirt will do, anything to break the pattern. The poor deer's eyesight is such that a plaid shirt breaks the edges enough so that they can not discern any difference between the foreground (the shirt) and the background (the woods).

Aside: Knowing human interactions of this kind, I might suggest that animals use a perception filter much like humans (not discrediting scientific info on the anatomy of the eye in both humans and deer), but that's for another thread, perhaps.

Would camouflage benefit the carrier outside of interactions with its predator/threat? Is there an example of camouflage working both against its aggressors and for its symbiotic relationships, in the same breath, to different sets of eyes?

Fun stuff!

[gusp]

Never heard of that. Usually it's either "hey look here I'm colorful or deadly" OR camouflage. But who knows how fish see other fishes. Some of them are really colorful to us and don't have poison. Maybe for other fishes they aren't as colorful or the color is distracting.