Urticating hair

A tarantula with visible urticating hairs

Urticating hairs are a defense mechanism found in some arthropods, notably certain species of tarantulas and caterpillars. These specialized hairs can cause irritation and discomfort to potential predators or threats.

Description

Urticating hairs are barbed bristles that can be released from the body of the animal. In tarantulas, these hairs are typically found on the abdomen and can be flicked into the air using the hind legs. The hairs are designed to irritate the skin or mucous membranes of predators, providing a means of defense.

Close-up of stinging hairs on a nettle plant

Types

There are several types of urticating hairs, classified based on their structure and function. In tarantulas, these are often categorized into types I through IV, with each type having a different shape and method of causing irritation.

Effects on Humans

Contact with urticating hairs can cause a range of symptoms in humans, from mild itching and redness to more severe allergic reactions. The severity of the reaction depends on the type of hair and the sensitivity of the individual.

Caterpillar with urticating hairs

Examples in Nature

Tarantulas

Many species of tarantulas, such as the Brachypelma smithi, possess urticating hairs. These spiders use the hairs as a primary defense mechanism against predators.

Brachypelma smithi with urticating hairs

Caterpillars

Certain caterpillars, like those of the Euproctis chrysorrhoea (brown-tail moth), have urticating hairs that can cause skin rashes upon contact.

Caterpillar with urticating hairs

Related Pages

• Tarantula
• Caterpillar
• Defense mechanisms in animals

References

• Marshall, S. D., & Uetz, G. W. (1990). The function of urticating hairs in the tarantula Grammostola rosea. Journal of Arachnology, 18(2), 143-150.
• Roth, V. D. (1993). Urticating hairs in New World tarantulas. American Arachnology, 47, 1-4.

• Euproctis Chrysorrhoea skin rash
  Euproctis Chrysorrhoea skin rash