Squirting Toxins Protect From Predators

a chubby green puss moth larva hangs upside down on a branch with a leaf

Biological Strategy

Puss moth

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Image: Patrick Clement / Flickr / Some rights reserved

Expel Liquids

There are various reasons living systems discharge liquids, such as to defend themselves, to avoid liquid buildup that can cause decay, to eliminate waste, or to dry off. Because liquids cannot be effectively moved through pushing, a different kind of force is needed to expel them. Creating that force requires energy, so living systems must have efficient strategies worth the energy investment or use an outside force (such as gravity). This typically entails strategies that build up pressure or use other forces to propel liquids away. An example of a living system that expels liquids is the scallop. This creature moves through water by clapping its shells together, generating a water jet that propels it in the opposite direction.

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Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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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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Tail filaments of Puss Moth caterpillars protect from predators by squirting formic acid.

Puss Moth (Cerura vinula) caterpillar showing 'face' and tail filaments

Puss Moth (Cerura vinula) caterpillar

Image: Bernard DuPont / CC BY SA - Creative Commons Attribution + ShareAlike

Puss Moth (Cerura vinula) caterpillar with tail filaments visible

“The pussmoth caterpillar browses head-down on leaves. Its body colour is exactly that of its food plant, but if an intruder shakes the branch, and alarms it, the caterpillar suddenly lifts its head from its meal, exposing a scarlet face. Simultaneously it protrudes a pair of blood-red filaments from its tail and squirts formic acid.” (Attenborough 1979:91)

Last Updated June 4, 2018

References

Book

Life on Earth: A Natural History

01/10/1981 | David Attenborough

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