Air Holes Protect From Dehydration

a large green caterpillar stands on a green leaf against a blurry brown background

Biological Strategy

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Image: Dean Morley / Flickr / Some rights reserved

Protect From Loss of Liquids

Water is essential to life. Liquids, mostly water, make up 70 to 90% of all living systems, and the loss of even a small percentage can mean the difference between life and death. Living systems must maintain a proper liquid balance, which is especially difficult in dry conditions. To do so, they must control the movement of liquids across their boundaries. Living systems do this using structures or waterproof materials to prevent or slow liquid movement. For example, when humans receive a cut, they must limit blood loss. Scattered throughout the bloodstream are lens-shaped structures that serve to plug the wound.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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The air holes of a moon moth caterpillar help avoid dehydration by closing to prevent evaporation.

“This portion of the body of a moon moth caterpillar shows the spiracles very clearly, ringed in red . The spiracles are equally distributed among its body segments, and can be closed if it is in danger of dehydration. Each new skin that it grows will have pores for the spiracles, which connect with a network of tiny tubes that carry oxygen deeper into its body.” (Foy and Oxford Scientific Films 1982:43)

Foy S, Oxford Scientific Films. The Grand Design: Form and Colour in Animals. Lingfield, Surrey, U.K.: BLA Publishing Limited for J. M. Dent & Sons Ltd, London; 1982. 238 p.

Last Updated September 14, 2016

References

Book

The grand design: Form and colour in animals

26/02/1983 | Sally Foy

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