![]() In mosquitoes and fruit flies, sound causes fine antennal hairs to quiver. Those detectors occur throughout the insect body but evolution typically only modified a single pair - apparently, almost any pair - to perceive the airborne vibrations generated by sound.įrom there on, each new attempt to forge ears went even further in its own direction as other structures were co-opted and reconfigured to capture, amplify and filter sound, extract the relevant information and convey it to the nervous system. This anywhere-goes approach might seem a little weird but there’s a simple explanation: In every case where an insect ear evolved, the starting point was an existing sensory organ: a stretch detector that monitors tiny vibrations when neighboring body segments move. Hearing has evolved at least 20 times in insects, leading to ears in an astonishing number of different locations, as shown on this image of a generalized insect. Praying mantises have a single, “cyclopean” ear in the middle of their chest. The bladder grasshopper has an abundance of ears with six pairs along the sides of its abdomen. Among moths and butterflies, ears crop up practically anywhere, even on mouthparts. Location is the most obvious difference between one insect’s ears and another’s: There are ears on antennae (mosquitoes and fruit flies), forelegs (crickets and katydids), wings (lacewings), abdomen (cicadas, grasshoppers and locusts) and on what passes for a “neck” (parasitic flies). All told, insect ears arose more than 20 separate times, a sure-fire recipe for variety. The 350,000 species of that most dazzlingly diverse group, the beetles, are almost all deaf, yet the few that have ears acquired them through two separate lines of evolution. Of the 30 major insect orders, nine (at last count) include some that hear, and hearing has evolved more than once in some orders - at least six times among butterflies and moths. These ancestral insects went on to diversify into more than 900,000 species, and while most remain as deaf as their ancestors, some gained the means to hear. When insects first appeared some 400 million years ago, they were deaf, Göpfert tells me. And thanks to some of this newfound knowledge, and an assortment of fossil insects, there’s even the tantalizing prospect of being able to eavesdrop on the ancient past, adding a new dimension to our understanding of the life and times of some long-vanished animals. Sensory biologists, acoustics experts and geneticists are working together to pin down how they all work, how and when they evolved, and why. But with the advent of new tools and technologies, ever more examples are coming to light. ![]() Most are hard to spot, if not invisible, and in many cases insects produce and sense sounds so far beyond our own range that we overlooked their abilities entirely. Amazing though katydid ears are, he tells me, they’re just one of many with astonishing capabilities: Evolution has made so many attempts at shaping ears, the result is a huge diversity of structures and mechanisms. Most moths have ears tuned to the frequencies used by bats.ĬREDIT: AVALON / PHOTOSHOT LICENSE / ALAMY STOCK PHOTOĬuriosity piqued, I call neurobiologist Martin Göpfert at the University of Göttingen in Germany, who studies hearing in the fruit fly Drosophila melanogaster. Yet obviously, some must hear: The summer air is filled with the trills, chirps and clicks of lovelorn crickets and grasshoppers, cicadas and katydids, all trying to attract a mate.Ī greater horseshoe bat hunts a moth. The appearance of bats that hunt with the aid of ultrasonic sonar drove the evolution of hearing in many moths and other night-flying insects. Insect eyes and antennae stand out, but ears? Even the eagle-eyed could be forgiven for wondering if insects have them. I’d never given much thought to insect ears until now. One Australian katydid has capitalized on its auditory prowess to capture prey in a very devious way: It lures male cicadas within striking distance by mimicking the female part of the cicada mating duet - a trick requiring it to recognize complex patterns of sound and precisely when to chip in.Īwesome? Absolutely. ![]() ![]() Katydids - there are thousands of species - have the smallest ears of any animal, one on each front leg just below the “knee.” But their small size and seemingly strange location belie the sophisticated structure and impressive capabilities of these organs: to detect the ultrasonic clicks of hunting bats, pick out the signature songs of prospective mates, and home in on dinner. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |