January 10, 2017
Illustration of California shield-back katydid (Capnobotes occidentalis) showing sound inputs that function remarkably similarly to the human hearing system.
When I was a kid, I dreaded the moment when a friend would call my name to wave me over to a school lunch table and I could not locate the sound of her voice. At a time in life rich with potential for abject mortification, the daily practice of standing in the middle of the cafeteria dumbly holding a plastic food tray with a panicked, lost expression ranks highly in those angsty and miserable moments of adolescence. If only I'd been a bush cricket.
Researchers from the University of Lincoln, UK, have discovered that a group of bush crickets, or katydids, have an “incredibly advanced hearing system” that enables them to locate the sound's origin with pinpoint accuracy. The study, published in the Journal of the Royal Society Interface, set out to explore how a bush cricket (Copiphora gorgonensis) native to Colombia, South America, is able to hear sound signals from potential mates and to detect the sound source. The research was conducted as part of a project to examine how insects have evolved incredible ultrasonic hearing abilities.
The nocturnal insects use the cover of night to conduct their amorous business. While the males sing to attract distant females, their potential mates' acute hearing abilities allow the females to find the most appealing male troubadours in the pitch dark of the rainforest. The bush crickets' ears are located in their forelegs, below their knees. Each ear has two eardrums, which are backed by a narrow tube that runs along the leg internally and opens out on the side of the insect's body. Dr. Fernando Montealegre-Z explained: “In mammals, ears are located on the sides of the head and their position and distance is enough to cause slight differences in the time a signal arrives, and also to produce amplitude differences between both ears. As these insects are too small to have ears in their heads, their location in the legs coupled with the tubing system allows the insect to hear a sound four times; twice in each ear.”
Jeffrey Cole, an NHMLA entomology research associate, explained in an email, "All katydids that have been examined have the same four-input sound receiving apparatus in both sexes. There is also a similar anatomy in crickets, and it is probably ancestral to all Orthoptera with long ovipositors (Ensifera). Grasshoppers (Caelifera) have an entirely different mechanism with an eardrum at the base of the abdomen on both sides."
Remarkably, katydid and human ears are not all that dissimilar. Cole says that the same researchers cited above showed in a 2012 paper that the fore tibiae of the Colombian bush cricket each have a fluid-filled channel like the mammalian inner ear. This shows, says Cole, that "mammal and insect hearing organs are totally different structures on different body regions, but the way they process sound is similar through convergent evolution!" The British researchers indicate that their findings might inspire other areas of research, such as engineering of microsensors that could ultimately lead to improvements in human hearing aids.
November 7, 2012
Have you ever jumped in your car and realized there was a bug on your windshield? Not a gross squished one, I mean a living one, ready for a hitchiking adventure. When this happens, you might be like me, and decide to spark up the engine and see how long that sucker can stick around for (never speeding of course)! In my extensive experience, the bugs usually manage to "hang on" for much longer than one would expect. Case in point: This bright green katydid—a close relative to grasshoppers—traveled with Nature Lab project manager, Jennifer Morgan, all the way from Palos Verdes to Pasadena, reaching speeds of up to 70 mph!
Katy "done" did it right!For a better idea of what a katydid looks like, here's an image courtesy of What's That Bug:
But why are they called katydids? According to Insects of the Los Angeles Basin, "Katydids are so named because of their supposed participation in a legendary love affair. Involved were two maidens: one was fair, the other (whose name was Kate) was more on the stately side. The masculine corner of the triangle, an anonymous lad, fell in love with the fair one and scorned the passions of Kate. When he mysteriously died, the question was: "Did or didn't the proud Kate do him in?" The insect lives today as the deceased's spirit, continually proclaiming the answer each summer night "Kate-she-did," or the variation "Katy-did."" So next time you're standing on a freeway overpass, look at all those cars speeding by and wonder, how many invisible hitchikers are passing by under your very nose? Furthermore, what are the conseqences of such movements? What happens to all those insects that are now 70 miles from their home?