Antipredator adaptation

Antipredator adaptations are adaptations developed over evolutionary time, which assist prey organisms in their constant struggle against their predators. There are several ways antipredator adaptations can be classified, such as behavioral or non-behavioral or by taxonomic groups.: detection, attack, capture and consumption. At each stage adaptations that maximize a prey organisms chances of survival have evolved, which in turn drives responding adaptions in their predators. This interaction over long periods of time is known as co-evolution.

Avoiding detection

For a predator to locate a potential meal, it must first identify a suitable prey organism. Prey, however, have many adaptive characteristics which make such a task difficult.

Nocturnality

Crypsis

Antipredator behaviors range from chameleons and octopuses that change color in order to better camouflage themselves, to crabs and geometrid moth caterpillars that decorate their bodies to help them hide, to Batesian mimicry in insects, to Thomson’s gazelles that stot so as to advertise unprofitability to predators, to selfish herd acts performed by adelie penguins when they attempt to enter water inhabited with leopard seals. Their behaviors are extraordinarily varied from species to species and some of them are quite odd; some prey actually fight back.

Avoiding capture

Three extremely odd defense behaviors are found in the sea cuke (cucumber), the Camponotus saundersi (Malaysian ant), and the horned lizard found in the desert southwest and Mexico. The sea cuke has a unique way of fighting off danger. Like other echinoderms the cuke has a type of collagen in its skin capable of excreting or absorbing more water effectively changing from a “liquid” to a “solid.” They can turn their bodies into mush, climb through small cracks and then solidify into small lumps so that they cannot be extracted. Their more desperate response is called evisceration. The cuke effectively turns itself inside out by excreting portions of its digestive tract and, on occasion, other organs like the respiratory tree or gonads. The cuke does this because its Cuvierian tubules, located in its hindgut, contain toxic chemicals. The toxins can actually kill other fish. Any predator that comes into contact with this noxious substance is likely to think twice about consuming the cuke. The cuke can then regenerate its digestive tract and continue to survive.

The horned lizard found in the desert southwest of the U.S. has an odd defense mechanism as well. When threatened the lizard increases pressure in its sinus cavities until the blood vessels in the corners of its eyes burst, squirting blood at the attacker.

Camponotus saundersi, an ant species found in Malaysia, also has a very interesting defense. The colony is divided up into different functional groups, one of which is soldier ants. These soldiers are charged with defending the colony at all costs. If battle ensues, these ants will actually self-destruct. They have two large glands that run the entire length of their body, and when they become stressed the ant contracts its abdominal muscles causing the glands to explode, spraying poison in all directions. These three examples seem to be some of the more bizarre ways that animals defend themselves against predation.

See also

• Alarm signal
• Predator satiation

References

Further reading

• Edmunds, M. 1974. Defence in Animals: A Survey of Anti-Predator Defences. Harlow, Essex & NY: Longman ISBN 0582441323
• Ruxton, G. D.; Speed, M. P.; Sherratt, T. N. (2004). Avoiding Attack. The Evolutionary Ecology of Crypsis, Warning Signals and Mimicry. Oxford: Oxford University Press. ISBN 0198528604