Karma Chameleon

The Rock Scientist at Mind Blowing Science has a fascinating post about animals. And while I’m sorely tempted to come over all E. L. Wisty (a character created by the late lamented Peter Cook) and talk about interesting facts, this post really is full of interesting facts. What’s more, they’re interesting facts that generate all sorts of evolutionary questions.

For instance, contrary to popular perception, the chameleon doesn’t change colours to blend in: they change depending on their mood, temperature, health, communication, and light. Which is all fair enough, but I find myself wondering what is the evolutionary advantage of using your whole body as a sort of mood ring. It’s understandable that they change colour when fighting: many animals have physical responses to make themselves look more fearsome. And having a coloration that advertises that you’re a healthy individual would be useful in attracting potential mates. But changing colour to advertise that you’re warm and happy seems rather odd.

Then there’s the poison arrow frog. Tiny and toxic, they rely on bright colours and patterns to warn predators that they’re not good to eat. While there’s a clear selective pressure here on the predators, in that the only ones that survive are the ones that don’t partake of a froggy nosh, it’s interesting to ponder whether the poison and colouring evolved together or one after the other. And it’s an unusual, and risky, evolutionary path to take: being incredibly toxic may help the species but it’s no comfort to the individual when the predator drops dead after eating them.

Finally, there’s the goblin shark – very aptly-named, as this monster can protrude its toothy jaws exactly like the Alien from Ridley Scott’s iconic movie series. I had to wonder, indeed, whether H. R. Giger, the artist who designed the creature, had the goblin shark in mind when he created the extendable jaws. The interesting thing about the goblin shark is that it looks prehistoric, just as many deepwater creatures do. The ocean deeps, being a fairly stable environment, impose fewer selection pressures, so once a species is able to survive they tend to continue without much change.

In addition to the Extendo-Jaws (TM) though, the goblin shark has a large, overhanging snout, which is studded with organs that detect electricity (see this reference). While this electricity-detecting snout is probably how it detects its prey, the disproportionate overhang may have been responsible for the development of the protrusive jaw: more sensors on a longer snout enables better prey detection, but only the creatures whose jaws can reach out from beneath the snout to eat the prey will actually survive.

So, all in all, some Interesting Facts about animals prompting some puzzling questions (puzzling to me, at least) about evolution. Which is what biological science is all about – some scientist looks at an aspect of the world and thinks to themselves “That’s weird, I wonder why it does that?” and proceeds to try and find out.

[Featured image: Veiled chameleon. Photo by Billybizkit, licensed under Creative Commons 3.0.]