Middle Ear Senses Barometric Pressure

a small brown fuzzy bat hangs upside down in a cave

Biological Strategy

Eastern pipistrelle bat

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Image: Dave Thomas / Flickr / Some rights reserved

Sense Atmospheric Conditions

For some living systems, the ability to detect changes in atmospheric conditions can be very valuable. By predicting changes in regional weather or in very localized conditions, living systems can avoid or take advantage of those changes. Since such adjustments can be very subtle, living systems must be able to detect miniscule variations in moisture, barometric pressure, ions in the air, and other environmental cues. Many insects and birds, for example, can predict oncoming storms and take cover before their lives are put at risk.

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Capture, Absorb, or Filter Organisms

Many living systems must secure organisms for food. But just as one living system must capture its prey to survive, its prey must escape to survive. This results in capture and avoidance strategies that include trickery, speed, poisons, constructed traps, and more. For example, a carnivorous plant called the pitcher plant has leaves formed into a tube that collect water. Long, slippery hairs within the tube face downward. When insects enter the tube seeking nectar, they lose their footing and slide inside, unable to climb out and escape being eaten and digested by the plant.

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Mammals

Class Mammalia (“breast”): Bats, cats, whales, horses, humans

Mammals make up less than 1% of all animals on earth, but they include some of the most well-known species. We know first-hand some of the characteristics that make mammals unique, like having hair, being able to sweat, and producing milk through mammary glands. Another critical shared feature is a set of highly-specialized teeth. Unlike sharks or alligators, for example, whose teeth are generally all the same size and shape, mammals have differently shaped teeth in different areas of the jaws to target specific foods or foraging strategies.

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The Vitali organ in the middle ear of the Eastern pipistrelle bat helps it hunt by sensing changes in barometric pressure that influence the number of insects flying at a given time.

“Bat researcher Dr. Ken Paige of the University of Illinois’s Institute for Environmental Studies noted that flying insects were most common when air (barometric) pressure was low (except in heavy rain). During these conditions eastern pipistrelle bats inhabiting caves in western Illinois came outside in large numbers. When the air pressure rose, however, insect numbers declined, and fewer bats exited the caves. The bat’s barometric sense may be due to the Vitali organ in the middle ear — bats are the only mammals with this organ.” (Shuker 2001:64)

Last Updated August 18, 2016

References

Book

The Hidden Powers of Animals: Uncovering the Secrets of Nature

26/02/2021 | Dr. Karl P. N. Shuker

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