Warning! Colors! Part 1: Aposematic Colors and Coral Snakes

or Aposematic Colors and Coral Snakes

Warning! Colors! Part 1: An Introduction to  Aposematics and Coral Snakes

"Although natural selection can act only through and for the good of each being,

yet characters and structures, which we are apt to consider as of very trifling importance,

may thus be acted on. When we see leaf-eating insects green, and bark-feeders mottled grey, ...

Hence natural selection might be effective in giving the proper colour...

and in keeping that colour, when acquired, true and constant.

Nor ought we to think that the occasional destruction of an animal

of any particular colour would produce little effect..."

Charles Darwin

On The Origin Of Species

Aposematic Coloration The term aposematic is a word whose Greek origin means keeping away and connotes eliciting a distaste for food. Using the term coloration in relation to the aposematic trait may be incomplete since the coloration of the animals with this attribute is mostly in association with patterns as well. The significance of this phenomenon has numerous and broad implications in ecology and evolution The notion of coloration as an adaptive trait and its importance as a phenotype for natural selection hasn't always been universally accepted (even after the publication of On the Origin of Species). A. F. Shull in "Evolution" (1936) suggests traits such as sexual selection, warning color and mimicry are insignificant and irrelevant to the point of being excluded from the doctrine of natural selection. Today, as Darwin originally did, biologists see the convergence of colors (and in some cases patterns) in clear association to ecological conditions as evidence for its role as a selected phenotype in a multitude of organisms. While there are many animals that have warning colors, coral snakes are a vividly colored and a perfect example of the adaptive value of being conspicuously colored and in effect honestly advertising or warning potential predators of an unpleasant, harmful or deadly counter attack.

North American Eastern Coral Snake Part 1: Intro to Aposematics and Coral Snakes Part 2: Evolutionary Explanations Part 3: Conspicuous Coral Snakes

Cobras are very present in Hindu lore, especially as kingly protectors. Pouring milk over a cobra during the Nag Panchami festival. AFP PHOTO/NARINDER NANU

Snakes in Mythology Eastern cultures have since ancient times revered snakes as immortals, protectors and especially as symbols of wisdom. The mythology of western cultures especially those of the Judeo-Christian, abound with references to the deceptiveness and threat of snakes. Without delving into the anthropological reasons as to why this is so, here's a well known expression to illustrate the point... The phrase "a snake in the grass" for most people conjures up an image of a sadistic creature disguising itself in order to inject venom into its hapless victim. That is to say, not for self-defense, not for food, but for evil pleasure. We even further emphasize the attitude, since they are poikilotherms, by calling this type of behavior 'cold-blooded". But, this is a cultural bias and just not true of nature. If fact we don't seem to be born with an instinct to fear snakes. it appears that is learned. Although I'll warrant that any snake will bite if only not to get stepped on. there is the ecological and evolutionary unsoundness of this sneaky snake scenario. There are many reasons why they don't really act this way, such as the energy costs of poison production, the lack of survival benefit, not to mention the potential loss of teeth and risk of infection just to name a few. The fact is, most snakes survive with the completely opposite strategy. Quetzalcoatl The Feathered Serpent  A Mayan Vision Serpent Virtually all snakes will seek to avoid confrontation with a predator, presumably since this is more cost effective for the snake, and being hidden (crypsis) is used for this purpose, as well as used for capturing prey. Venomous snakes in particular, especially in encounters with potential predators, indicate their presence and in fact draw attention seemingly as a warning precisely in order to avoid a confrontation. Colors are often a warning but so too is rattling a tail, puffing up a hood and hissing. Snakes are in general silent, the hissing is a warning. Now, ask yourself this question, if these snakes really wanted to ambush you for no reason... would it even have these warning signals?

Meet Mr. Coral Snake & Family The coral snake is really several species all belonging to the genus Micrurus, of the cobra family Elaphidae. The are generally small (maximum recorded length about 5 feet) with a common length between 18 inches and 2 feet. Their distribution ranges throughout the world in tropical, subtropical and neotropical regions. They usually live in forests but are also found in grass lands and deserts. Like virtually all these kinds of snakes (with the exception of a few cobras, which are arrogant) they are secretive and docile. In fact they will generally not bite humans unless stepped on, picked up or disturbed. All coral snakes are diurnal, thus they have round eyes similar to non-venomous snakes rather than the ovals of nocturnal (and most other venomous) snakes. Coral snake eyes also have similar oil drops as birds, aiding their color vision for certain wavelengths of light. The head of all coral snakes is blunt, the scales smooth and glossy. Micurus flavius (eastern coral snake) of the United States are banded in triads with alternating wide bands of red and black separated by narrow stripes of yellow. It is from this coral snake that the infamous phrase "red touching yellow is a dangerous fellow is derived. The pattern and order generally hold true although there are variations in proportion and intensity. Some species of coral have demonstrated melanism and others toward albinism especially with the yellows tending to white in the western species. But remember, this order of colors only applies to these snakes in North America!  On other continents coral snakes do not necessarily follow this pattern. Like all snakes, coral snakes are carnivores. They are extremely quick and nimble, preying specifically on other snakes, yet they may take lizards and other reptiles. Prey are killed by venom only if the prey is dangerous. The venom is highly neurotoxic though small in quantity.

Coming up in future posts, more about coral snakes, how conspicuousness  or cryptic their pigments can be and the evolutionary factors in their aposematic coloration.

You might also like: / Warning! Colors! Part 2 / Warning! Colors! Part 3 /
Enjoy.
© 2012 MU-Peter Shimon