Bug-Eared: Human and Insect Ears Share Similar Structures
2012 11 22

By Marissa Fessenden | ScientificAmerican.com

In a noteworthy example of convergent evolution, Katydid ears have evolved components resembling those of humans, albeit on a much smaller scale



A rainforest katydid has ears that evolved to be remarkably like those of humans and other mammals. The insect’s hearing organ, although tucked in the crook of its front legs, has components that echo the structures of our own middle and inner ear, researchers have discovered.

In humans the outer portion of the ear gathers sound waves and funnels them toward the thin membrane of the eardrum, also called the tympanic membrane. The eardrum’s vibrations translate the pressure waves of sound to the three smallest bones in our body—the hammer, anvil and stirrup bones—which shake against a snail shell-shaped organ called the cochlea, whose curves are lined with sensory-cell hairs. The wiggling bones outside jiggle liquid inside the organ and trigger those cells, which send signals to the brain via the auditory nerve. Hair cells that respond to high frequencies are closest to the origin of wave propagation and cells that respond to low frequencies are located deeper within the cochlea.

Copiphora gorgonensis is a yellow-orange–faced katydid from Gorgona Island in Colombia. The insect’s hearing organ comprises a tympanic membrane that connects to a thin cuticle plate. Sound waves rock the tympanum and thus the cuticle plate like a seesaw. But the seesaw is lopsided, with the fulcrum closer to one end. This setup translates larger movements from air pressure waves to smaller, more powerful motions in the cuticle plate. The plate creates ripples in a fluid-filled chamber akin to an unfurled cochlea. Inside this chamber sensory cells are arranged like a keyboard from high- to low-frequency sensitivity.



The cuticle plate plays the same role as the tiny hammer, anvil and stirrup of mammalian ears, but in miniature. The katydid’s entire ear spans just 600 microns, a U.K.-based research team reports in the November 16 issue of Science. (A micron is one millionth of a meter.)

[...]

Read the full article at: scientificamerican.com






Related Articles


Latest News from our Front Page

Is Michael Brown A National Hero?
2014 08 19
From: Brother Nathanael: I don’t know about you but I revolt against crowning Michael Brown a “national hero.” Better the crown go to Darren Wilson who according to the Ferguson Police Report shot Brown in self-defense. Yet there’s already a bounty on his head. And the media eats it up. For whether it’s NBC; CNN …or the New York Times; the spin is that ...
Toxoplasmosis – The Revealing Behavior and Effects of Parasites
2014 08 19
A fascinating interview with neurobiologist Robert Sapolsky on toxoplasmosis and the behavior of a seemingly intelligent parasite. The parallels to archonic-type influences are astounding. A must see. From: zengardner.com For context, please listen to John Lash on White Genocide & The Archontic Infection
Emmy Awards 2014 - Spoilers! Leaked Clip for Best Psychopath!!
2014 08 19
WARNING SPOILER ALERT!!! Leaked clip from the 66th Annual Emmy Awards scheduled to air August 25th, 2014. Winner announced for best Psychopath of the year! Video from: youtube.com Can’t get enough of those warm Zionist in Hollywood. Joan Rivers: "Palestinians deserve to be dead"
UN calls for tests on passengers in Ebola crackdown
2014 08 19
Health workers wearing protective clothing prepare to carry an abandoned dead body presenting with Ebola symptoms at Duwala market in Monrovia. Ebola-affected countries should immediately begin exit screening all passengers leaving international airports, sea ports and major ground crossings, the UN health agency urged yesterday. The risk of the Ebola virus being transmitted during air travel is low because, unlike infections ...
Ebola-infected patients driven from treatment centre in Liberia
2014 08 19
Whereabouts of 29 patients unknown after quarantine centre is attacked by men claiming "there’s no Ebola in Liberia" A health worker assists a colleague with protective gear, as they collect the body of a man suspected to have died from the ebola virus, in Monrovia, Liberia, Photograph: Abbas Dulleh/AP Armed men claiming that "there’s no Ebola" in Liberia raided a quarantine centre ...
More News »