When we start studying nature, a lot of strange and intriguing aspects come to light. There are so many signals, signs, and all sorts of factors that help animals, plants, and insects to survive and continue their life cycle.
For instance, many birds have a sort of auditory signal to warn their friends when there’s a predator nearby. However, the coloring of many living creatures is what really stands out. Most of us are already familiar with the concept of camouflage. This is where an animal, insect, or even a plant has coloring to help it blend into its surroundings. The blending means that predators won’t be easily able to spot their prey, thus increasing the likelihood of survival for the weaker creature. On the other hand, some form of camouflage can also help out a predator; concealing them so that they can sneak up on their intended prey.
Aposematic coloration, however, is the opposite of camouflaging colors. Instead of making a plant, insect, or animal blend in, it makes them stand out. This way, it actually advertises that the living tithing is not worth the risk of attacking or consuming.
Aposematism itself is a more general concept, which can refer to any way in which an animal exhibits its own toxicity. The defences could include venom, sharp spines, an aggressive nature, a foul taste, or an overly strong scent. The rattle of a rattlesnake is one example of an auditory form of aposematism. These characteristics are beneficial for both prey and predator, as both will come to harm if the animal with the aposematic signals is attacked.
Etymology of Aposematism
The term ‘aposematism’ comes from the Ancient Greek teams ‘ἀπό apo’ and ‘σῆμα sēma’, which mean ‘away’ and ‘sign’ respectively. Edward Bangall Poulton, an English biologist coined the term in his book ‘The Colors of Animals’, which was published in 1980.
The Function of Aposematic Coloration
The main purpose of a living creature having aposematic coloration is to warn off any potential predators as soon as possible. The creature in question might be poisonous, foul-tasting, or have some other characteristic that makes it unpalatable.
Most aposematic signals are the visual kind; bright colors, patterns in high contrast, and so on. A poisonous snake, for instance, might have stripes that can be spotted from far away. The stripes will probably be in bright colors that show up well in contrast to one another.
Usually, the more conscious and brightly-colored an organism is, the more toxic it’s likely to be. There might also be some very strange and unusual insects that display such warning signs.
This is not to be confused with deimatic display, which just startles predators with a seemingly dangerous appearance. A certain kind of moth, for instance, has starling patterns on its wings. The eyespots are very pronounced when the wings are fully spread out. While the moth itself has no other defences against its prey and is not toxic for most of them, displaying its wings will make most predators sense a threat. Even if their hesitation is sleight, this might be enough for the moth to escape.
The Most Common Warning Colors
The world’s deadliest insects, animals, and even plants have warning colors that stave off predators. Some colors are more common for this warning purpose than others, with the most effective ones being black, red, white, and yellow. Such colors give off a powerful contrast against green foliage. Plus, they also resist changing according to lighting or shadows. They’re very chromatic and might even provide some camouflage when viewed from a distance.
Aposematic coloration might also evolve along with the light conditions, background, or predator vision. Some of the visual signals can be accompanied by certain sounds, behaviours, or odors that get the message across as best as possible. A good example here is the skunk; it’s colored black and white as a warning. Along with this, it has an aggressive nature and also releases a foul odor when threatened. A ladybird also has several aposematic warnings; the black spots on red are the coloration signal, while the yellow fluid it releases is both an olfactory and gustatory warning (since it both smells and tastes unpleasant).
For insects, the warning colors are most likely to deter birds as their main predators. Even these strange and unusual birds will probably be deterred by a strong warning corporation.
Behaviours of Animals With Aposematic Coloration
Animals that have bright colors in their appearance usually tend to move relatively slowly. They’re not too worried about exposing themselves to predators, as it’s their exposure that advertises their defence system. The color of their skin, fur, or scales are one thing; while their chemical weapons are their secondary defence in case a predator doesn’t get the first hint.
One good example here is the grasshopper known as Aularches miliaris. This organism usually mates and lays eggs in October and is usually regarded as a pest that can destroy harvests. Its defense mechanism is not too impressive; its movement is sluggish and slow, with the ability to only make short leaps. Its coloring also makes it very conspicuous on vegetation, but it’s just the primary warning sign for predators. If this grasshopper is disturbed or attacked, however, it can defend itself by emitting a sharp, raspy voice. In case the predator pinches its thorax, the grasshopper then squirts out a clean, thick mucus that has a bitter taste and unpleasant smell. The number of bubbles inside gives this mucus a foam-like appearance. It releases in a strong jet-like stream from the thorax, and more slowly from other parts of its body. The foam can even partially cover up the grasshopper.
Examples of Aposematic Coloration
Below are some specific examples of organisms with different types of aposematic coloration:
Velvet ants, which are parasitic wasps, are brightly colored. If grabbed, they can make audible noises for increased warning.
Large milkweed beetles have a warning red and black pattern; the nymphs consume toxic elements from the host milkweed plants so any predator will likely come to harm from eating them
The barber pole grasshopper also has a warning color that tells potential predators of its unpleasant taste.
Most bees, wasps, and even some butterflies have bright coloration, and most are also foul in taste for predators. The same goes for the larvae of butterflies and moths.
Tree frogs are brightly colored, and are usually poisonous. Their poison might range from mild to extreme, with the colors varying accordingly.
The blue ringed octopus is also highly venomous, and its coloring warns predators in the water. The conspicuous spots on it are another warning sign, which is also true of several spotted organisms in nature. This is probably where some people’s trypophobia evolves from as well (the fear of tightly packed holes, spots, or rings).
Aposematic coloration is apparent in many animals, especially those who might need some extra help in defending themselves. Mammals, reptiles, plants, and insects can show us examples of this phenomenon. In some cases, the coloring might work as both a warning sign and a mating signal. Whatever the case, it’s certainly an interesting occurrence that we should be aware of.