Читать книгу Extreme Nature - Mark Carwardine - Страница 17

NAME	polyphemus moth Antheraea polyphemus
LOCATION	North America
ABILITY	a male can detect a female on the evidence of just one molecule

© Jeff Lepore/Science Photo Library

Many animals rely on their sense of smell to find food or a mate and even to find their way around. Some live in places where other senses are of little use – eyes don’t help much if you spend most of your life in the dark, and ears would be hopeless in a particularly noisy environment – so they rely on smell more than most.

Some animals, such as sharks, are selective in their smelling abilities and are super-sensitive to significant smells that are relevant to activities such as feeding or breeding. In fact, smell is so important to sharks that they have been dubbed ‘swimming noses’. Their smell receptors are fine-tuned to picking up small concentrations of fish extract, blood and other chemicals – but so are the receptors of many other animals. Some catfish have such super-receptors that they can smell compounds at 1 part to 10 billion parts of water.

The likelihood is, though, that moths are the record-holders, especially the males. They use their antennae to home in on the sex pheromones, or chemical allures, released by females and can even detect if these females are on plants suitable for egg-laying. Some females release deviously small amounts of pheromone, to make sure that only those males with the most highly tuned antennae can follow the trails. The likely record-holder for the best known sense of smell is the polyphemus moth: just one pheromone molecule landing on a male’s antennae will trigger a response in his brain.