Rainforest Diversity

THE ARTS OF DECEPTION: MIMICRY AND CAMOUFLAGE

MIMICRY

Batesian Mimicry

Batesian mimicry is named for Henry Walter Bates, a British scientist who studied mimicry in Amazonian butterflies during the mid- and late nineteenth century. Batesian mimicry refers to two or more species that are similar in appearance, but only one of which is armed with spines, stingers, or toxic chemistry, while its apparent double lacks these traits. The second species has no defense other than resembling the unpalatable species and is afforded protection from certain predators by its resemblance to the unpalatable species, which the predator associates with a certain appearance and a bad experience. Examples of Batesian mimicry are the several species of butterflies that mimic the toxic Heliconid butterflies. Another fascinating butterfly mimic is the non-toxic Papilio memmon of Indonesia. Each female butterfly (regardless of her coloration) can produce one or more different female forms which mimic any of five other species of foul-tasting butterflies. Batesian mimicry is also found in venomous coral snakes and the harmless milk and king snakes of the New World. Both snakes are marked with alternating yellow, red, and black bands causing possible predators to avoid both. The snakes can often be distinguished by using an old scout saying: "Red against yellow: kill a fellow. Red against black: friend to Jack." The deadly coral snake has bands in the order of red, yellow, black, while the innocuous species have the pattern of red, black, yellow (although the rule is not failsafe and there are exceptions).

Muellerian Mimicry

Muellerian mimicry is named for Fritz Mueller, a German zoologist who worked in the Amazon three decades after Bates. This form of mimicry refers to two unpalatable species that are mimics of each other with conspicuous warning coloration (also known as aposematic coloration). Thus all mimics share the benefits of the coloration since the predator will recognize the coloration of an unpalatable group after a few bad experiences. Since several species have the same appearance to the predator, the loss of life will be spread out over several species, reducing the impact on each individual species. Poison arrow frogs of South America and Mantella frogs of Madagascar are examples with their conspicuous coloration of bright colors against black markings and toxic composition.

Self Mimicry

Self-mimicry is a misleading term for animals that have one body part that mimics another to increase survival during an attack or helps predators appear innocuous. For example, countless moth, butterfly, and freshwater fish species have "eye-spots": large dark markings that when flashed may momentarily startle a predator and allow the prey extra seconds to escape.
"Eye-spots" also help prey escape predators by giving predators a false target. A butterfly has a better chance of surviving an attack to the outer part of its wing than an attack to the head.

Less often predators utilize self-mimicry to aid in catching prey by appearing less threatening or fooling the prey as to the origin of the attack. For example, several turtle species and the Frogmouth Catfish (Chaca sp.) of Southeast Asia have tongue extensions that are used as a sort of lure to attract prey to a position where they become an easy catch. One of the most interesting examples of self-mimicry is the so-called "two-headed" snake of Central Africa which has a tail that resembles a head and a head that resembles a tail. The snake even moves its tail in the way most snakes move their heads. This adaptation functions to trick prey into believing the attack is originating from where it is not.

CAMOUFLAGE

A completely different approach for deception is camouflage, whereby animals seek to look inanimate or inedible to avoid detection by predators and prey. There are many examples of rainforest species which are cryptically colored to match their surroundings. For example, the Uroplatus geckos of Madagascar are incredible masters of disguise and are practically unnoticeable to the passer-by. An even more amazing group is the katydids, a group of grasshopper-like insects found worldwide. Katydids are nocturnal insects which use their cryptic coloration to remain unnoticed during the day when they are inactive. They remain perfectly still, often in a position that makes them blend in even better. Katydids have evolved to the point where their body coloring and shape matches leaves?including half-eaten leaves, dying leaves, and leaves with bird droppings?sticks, twigs, and tree bark. Other well-known camouflage artists include beetles, mantids, caterpillars, moths, snakes, lizards, and frogs.

Some species appear to have conspicuous coloration when they are not in the proper surroundings. For example, among the brilliant butterflies of the forest, the magnificent electric blue Morpho, has iridescent blue upper wings and a seven-inch wingspan. However, because the underwings are dark, when the Morpho flies through the flickering light of the forest or even out in broad daylight, it seems to disappear. Other forest species, especially mammals, have spots or stripes to help break up the animal's outline. In the shade created by the canopy, large mammals like leopards, jaguars, ocelots, and okapi are surprisingly difficult to see with their disruptive coloration.

Review questions:

• What are three types of mimicry?
• Why is camouflage important?

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