For horseshoe bats, wiggling ears and nose makes biosonar more informative

Date:  April 6, 2017

Source: Virginia Tech
 

Humans, and most other mammals, have just four muscles joining their ears to their head. Bats have more than 20, and they use them to execute a precise series of wiggles, swivels, and twitches.

"In one-tenth of a second, three times as fast as you can blink your eyes, the bats can change the shape of their ears," said Rolf Mueller, an associate professor of mechanical engineering at Virginia Tech.

Mueller is the lead author of a new study, published in Physical Review Letters, demonstrating that these quick, precise movements underlie the bats' ability to wend their way through their world.

Bat echolocation is one of nature's remarkable achievements in navigation.

Continued

Horses' mobile ears are 'communication tool'

5 August 2014 Last updated at 07:45

By Victoria Gill

Science reporter, BBC News

Very mobile ears help many animals direct their attention to the rustle of a possible predator.

But a study in horses suggests they also pay close attention to the direction another's ears are pointing in order to work out what they are thinking.

Researchers from the University of Sussex say these swivelling ears have become a useful communication tool.

Their findings are published in the journal Current Biology.

The research team studies animal behaviour to build up a picture of how communication and social skills evolved.

"We're interested in how [they] communicate," said lead researcher Jennifer Wathan.

"And being sensitive to what another individual is thinking is a fundamental skill from which other [more complex] skills develop."

Ms Wathan and her colleague Prof Karen McComb set up a behavioural experiment where 72 individual horses had to use visual cues from another horse in order to choose where to feed.

They led each horse to a point where it had to select one of two buckets. On a wall behind this decision-making spot was a life-sized photograph of a horse's head facing either to left or right.

In some of the trials, the horses ears or eyes were covered.

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Mysterious Attacks Leave Livestock Earless in Kentucky

An unknown animal is attacking, but not eating, livestock in Kentucky, leaving many of the victims with gnawed or detached ears.

According to WAVE News, the attacks have been ongoing for several weeks in Shelby County, Ky. At least five goats have had to be put to sleep due to their injuries, and a goat named Polka-dot has been left with just one ear.

Kevin Cox, the local farmer who owns Polka-dot, has also had several of his bulls attacked, he told the news organization.

Read on:  http://www.livescience.com/25728-mysterious-livestock-attacks.html

Fatty Ears May Help Baleen Whales Hear

The remains of stranded minke whales, mostly from Massachusetts beaches, have helped scientists understand how they and their close relatives hear.

Minke whales are baleen whales, whales that use baleen plates in their mouths to filter meals of tiny organisms out of the ocean. Scientists have known for some time that their relatives, the toothed whales including killer whales, sperm whales and dolphins, use fat associated with their lower jaws to guide sound into their ears. Land animals use air-filled ear canals to do the same thing.

Using a combination of scans and dissection, a team of researchers found the baleen whales have similar lobes of fat that appear to provide a direct conduit for sound to the middle and inner ear.  

Continued:  http://www.livescience.com/19733-fat-ears-baleen-whales-hearing.html

Fossils Reveal Secrets of Insects' Weird Ears

Various species of insects boast ears in the strangest places, including on their necks and under their wings. Now, a new examination of 50-million-year-old cricket and katydid fossils finds that these odd ears evolved before even the appearance of the predators that these ears can hear.

Crickets, moths and other flying insects can hear the ultra high-pitched sonar of hunting bats, a talent that helps them avoid being eaten. Researchers suspected that the appearance of bats on the scene triggered the evolution of these sensitive ears. But the new research reveals that crickets and katydids had modern ears 50 million years ago, before echolocating bats evolved.

"Their bat-detecting abilities may have simply become apparent later," study researcher Dena Smith of the University of Colorado, Boulder, said in a statement.

Insects have evolved ears at least 17 times in different lineages, and other insects, such as the blue morpho butterfly, may even be able to distinguish between low and high pitches with their primitive under-wing ears. But the fossil record has been too sparse to determine whether bats can take credit for certain bugs' hearing boost.

http://www.livescience.com/17721-fossil-insect-ear-evolution.html