Stress saves

Stress hormone helps animals change shape to evade predators

Published: Sunday 31 March 2013

Brian GratwickeANIMALS can alter their morphology, physiology and development with changes in their environment, a phenomenon known as “phenotypic plasticity”. But until now, nobody knew the mechanism behind such responses.

A study has now shown that stress hormones can help developing animals alter their body shape to evade predators. These hormones are the ones that prepare organisms to defend themselves or escape from dangerous situations, like an attack by another animal—the so-called fight-or-flight response.

Researchers at University of Michigan have now, through a series of experiments, demonstrated that when tadpoles are exposed to a stress hormone for long periods of time, their tails grow longer to make them better at avoiding lethal attacks by predators, such as dragonfly larvae.

The study, say the researchers, is the first clear evidence that stress hormone corticosterone, similar to the human stress hormone cortisol, produced by tadpoles causes the morphological changes to help them improve their survival skills in hostile environment.

The findings of the study, published online on March 5 in Proceedings of the Royal Society B, are surprising as in adult vertebrates, including humans, prolonged exposure to stress hormones inhibits the growth of tissues.

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