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A beginner naturalist when walking into the tropical rainforest may discover that there is actually few species of animals to see. But how can this be? Large animals may indeed be scarce, but small animals are all around. The rainforest is full of colour tricks, played by animals trying to escape predation. Many have evolved to produce pigments that will help them to blend into their surroundings. Some insects even go through all the trouble to duplicate the bud scars and bark texture of the twigs on which they feed and hide. Brassolid butterflies and katydids are able to look like leaves in various stages of life, from the bright green bud to a decaying brown leaf. Insects that mimic dead leaves even mimic the minute details like the network structure of leaf veins and spots of fungal decay. Katydids are coated with green extrusions that look exactly like lichens and losses that are on the trees. Some caterpillars even look like bird droppings to escape being eaten by birds. Another insect than blends into their surrounding is the praying mantis. Praying mantis comes in diverse numbers. The Chinese praying mantis is green in colour and the most common. Its body looks just like a leaf. The orchid mantis on the other hand looks just like an orchid. When staying completely still it is near impossible to spot it. This strategy not only enables it to hide from predators, but also from prey. A potential prey may be unaware of its presence and just walk into the spiny forearms of the praying mantis. Butterflies, often adorned with bright waving patterns on their wings are always strikingly obvious during their flight. Thus whenever they fly they are calling for attention to potential predators. However to tackle this problem, some tropical butterflies have transparent wings, rimmed with black and grey, a colour pattern that blends well in the dim forest under-storey. For those living in the higher canopy, where sunlight is able to pass through, their wings are dark with bright orange, yellow and white that blends in the sun dappled surrounding. With so many insects all blending themselves into the surroundings, birds have developed certain tactics to help them find their prey. The principle behind this is to focus and be specific about what you are looking for. For example, when searching for strawberries in the bushes, an efficient picker who only look out for flashed of red that represents a ripe strawberry would be more productive than a daydreamer whose eyes linger around his surroundings. Using this concept, birds rule out non-important details and only look out for specific shapes or colours. This helps them to locate prey with greater efficiency, even though the range of varieties of food they catch is limited using this tactic. To counterstrike, or rather make use of this weakness in birds, many insects have adopted unusual shapes, colours and form to be out of the list of things, bird focus on. Examples include moths that have twisted wings, hair-like tufts protruding out from the wings, and odd resting positions. Predators have learned to avoid animals with bright colours over time, knowing it will not make a good meal. Such animals include the coral snake and the poison arrow frogs. (For more information on this type of strategy of warning the predator, visit the section on "warning colours"). However, some harmless species of animals mimic the colour pattern of that of a poison species to avoid being eaten. For example, the coral snake of tropical America advertises it poison through the bands of yellow, red and black. Some snakes which are either completely harmless or with weak venom adopt similar colour patterns. One being the king snake. |
