In my last blog post I talked about cryptic coloration, which has obvious adaptive benefits. Why then are there bright animals? Why the peacock (Pavo Sp.)? Why so many absurdly bright hummingbirds? Why Drill monkeys with vivid red and blue markings? The answer in one word: sex. Although sexual advertisement isn’t the only reason an animal may be bright either. One may just as readily ask, why the blue morpho (Morpho sp.) butterfly? Why the poison dart frogs (family Dendrobatidae)? This time, the answer is a little more complex but we’ll start with warning coloration.
A blue morpho, many other butterflies and poison dart frogs are brightly colored for the same basic reason coral snakes (genera Micrurus, Micruoides and Leptomicrurus) are brightly colored. All these creatures are brightly colored to provide a memorable warning: stay away. Birds that eat toxic butterflies don’t die but they get sick and vomit the meal back up. A study by Lincoln Brower showed that blue jays only take one or two tastes to remember to never eat a brightly colored toxic butterfly. Here’s where it gets complicated though, because not all brightly colored butterflies are toxic but most birds won’t eat them anyway. Being colored like something toxic is an evolutionary short cut, it presumably takes less energy input to simply change your color than to change your color and develop toxicity. A butterfly that looks like the toxic monarch butterfly (Danaus plexippus) won’t likely be eaten by a bird with the hard knowledge that monarch’s don’t go down too easy. This is a specific type of mimicry called Batesian Mimicry after the Amazonian explorer naturalist Henry Walter Bates. There are some butterflies that mimic each other while both being toxic. The reason that they would mimic each other seems to be one of cost sharing. Even in a toxic species of butterfly, such as the monarch, some individuals must be sacrificed to teach birds (or other predators) that they’re not palatable. If two types of butterflies are equally toxic and look similar enough to each other, less of each species will have to be sacrificed to teach young fool-hardy birds a lesson and both species benefit. This type of mimicry is called Müllerian mimicry, after Fritz Müller.
Of course when it comes to coral snakes, unlike with butterflies or poison dart frogs, palatability isn’t the real issue but one of venom injected into an aggressor. Still, the message is largely the same: try to eat me and you’ll regret it, accidentally step on me and you’ll regret it. Also with snakes, the same mimicry types and their adaptive benefits apply. I talked about the elegant snail eater a few blogs posts ago and how I thought it might be a coral snake at first. The snail eater is a perfect example of Batesian mimicry, the snake looks like its much more dangerous relative the coral snake, and so is somewhat protected from predation.
Several species of coral snakes being colored in a similar pattern of bright red, yellow and black while all bing venomous is a great example of Müllerian mimicry (or possibly automimicry).
I’ve included pics of some of the most colorful organisms we’ve discovered and I’ve managed to photograph while at Reserva Las Tangaras. I hope you enjoy them and take time to consider why each one is so bright.