虎蛾和蝙蝠

onlyuhaibo

Bats are active at nights. Most of them hunt for insects by sending high pitched sounds (Sound is made by vibrating things. The faster things vibrate, the higher the pitch. The rate at which vibrations are produced is, pitch).

Bats produce sounds by their mouth or nose. When the sound waves hit an object an echo comes back. The bat’s ears have a complex set of folds that help determine the position of the object. Based on the intensity of echo, a bat can know how big an object is. A smaller object will reflect less sound waves and the echo will be small. If the object is an insect, the bat can know in which direction the insect is moving. A lower pitch echo will mean that the insect is moving away and a higher pitch will mean the opposite. This mechanism is known as echolocation. Bats navigate themselves and hunt insects by echo locating objects and prey. A wide variety of insects are eaten by bats, except Tiger moths.

Tiger moths belong to the family Arctidae. They are world wide in distributio0n. Most of them are night fliers. They derive their name from their bold contrasting coloration of gold and black, resembling the stripes of a tiger. The wings are thin and elegant, having fine scales and a span of ¾ to 3 inches. The larvae of Tiger moths, the woolly bears feed on a variety of plants and accumulate toxins in their skin. Adult moths acquire these toxins. They are therefore bad tasting insects.

The Tiger moth has survived bat predation over millions of years. The moth has a special organ called Tymbal organ on its meta thorax. This organ has thin membranes which are vibrated to produce ultrasonic sounds (high pitch sounds similar to bats that humans cannot hear).The moth has also a Tympanal organ on the thorax which functions as a hearing organ.

With this apparatus, the Tiger moth is capable of hearing bat’s sounds. It evades the bat, by a series of evasive maneuvers of loops, spirals and dives. It produces high frequency click sounds or squeaks. These sound waves perceived by the bat as multiple echoes, leave the bat confused and unable to locate or target the moth.

It was earlier believed that the Tiger moth jams the sonar system of bats by its ultrasounds. But experiments have revealed that the Tiger moth is more intent on making its presence felt by its sounds and warn the predator of its toxins and bad taste. It is more a chemical message to bats to seek their dinner somewhere else.

The aerial battles of Tiger moths and bats continue to baffle scientists.

onlyuhaibo

这篇比较考普÷

oths Mimic Sounds To Survive

ScienceDaily (May 30, 2007) — The research was conducted by Jesse Barber, a doctoral student in biology at Wake Forest. William E. Conner, professor of biology at Wake Forest, co-authored the study.

est University study. This is the first study to definitively show how an animal species uses acoustic mimicry as a defensive strategy.

The research was conducted by Jesse Barber, a doctoral student in biology at Wake Forest. William E. Conner, professor of biology at Wake Forest, co-authored the study.

In response to the sonar that bats use to locate prey, the tiger moths make ultrasonic clicks of their own. They broadcast the clicks from a paired set of structures called “tymbals.” Many species of tiger moth use the tymbals to make specific sounds that warn the bat of their bad taste. Other species make sounds that closely mimic those high-frequency sounds.

“We found that the bats do not eat the good-tasting moths that make the similar sounds,” said Barber, who has worked on this research for four years.

In the study, other types of moths that were similar in size to the sound-emitting moths, but did not make sounds, were gobbled up by the bats.
The researcher trained free-flying bats to hunt moths in view of two high-speed infrared video cameras to record predator-prey interactions that occur in fractions of a second. He also recorded the sounds emitted from each moth, as well as the sounds made by the bats.

All the bats quickly learned to avoid the noxious moths first offered to them, associating the warning sounds with bad taste. They then avoided a second sound-producing species even though it was not chemically protected. This is similar to the way birds avoid butterflies that look like the bad-tasting Monarch.

The two species of bats used were big brown bats and red bats. Barber raised the bats in the lab so behavior learned in the wild would not influence the results of the experiment.

Barber said anecdotal observations have suggested that animals such as snakes, owls and bees use acoustic mimicry. This study takes the next step and provides the definitive experimental evidence for how mimicking sounds helps an animal survive.

This research is to be published in the May 29 issue of the Proceedings of the National Academy of Sciences.

Email or share this story:

fqy1988

DDD

zliycdr

这篇放出来是想和哪篇匹配？楼主标明下谢谢

onlyuhaibo

还想还没整理到沟里，我是看到有个筒子说考到了这一个，根据他的描述找的