State of the Planet

News from the Columbia Climate School


How Bloodthirsty Creatures of The Night See

Bat hanging upside down
Photo of Fruit Bat by Flickr user davidw

While they instill fear and disgust into many, they are also a great source of myth and imagination, inspiring famous characters like Dracula and Batman. Beyond the eerie exterior and misunderstood persona, both of which drive biologists batty, these creatures of the night are incredibly complex and diverse and vital to the functioning of the world’s ecosystems.

It is myth that all bats are bloodsucking villains of the night. In fact, most bats prefer to dine on fruits, nectar, or insects. There are however, some vampire bats that will make a small cut into a sleeping animal and slurp up some of the blood from the wound.

Bats help control the rising numbers of many insects that attack crops on farms and reduce our need to use harmful chemicals that kill insects. Despite their value, according to an article produced by the United States Fish & Wildlife Service, bats rank among the most endangered species. In fact, of the 45 kinds of bats that live in the United States, seven are in severe risk of becoming extinct.

Bats are nocturnal (only active during the night) because they have adapted to a lifestyle of avoiding predators that hunt during the daytime. In order to find flying bugs to prey on, such as mosquitoes and moths, bats use a remarkable navigation system called biosonar, also known as echolocation. Like bottlenose dolphins, killer whales and shrews, bats also use this process to gain information about their surroundings.

The unique physiology of bats, fine-tuned by evolution over millions of years, allows them to utilize echolocation to navigate space with seamless precision. The process is as follows: bats move air past their vocal chords to create a sound so high it is outside the human hearing range. The vibrations quickly travel through the air and eventually bounce off of an object. Then, they travel back to either the left or right ear (depending on which is closer to the sound) and then to a series of complex folds in the outer ear that help determine the vertical position of the object. The intensity and pitch of the echo help bats identify the size and type of animal and the direction in which it is moving.

A New York Times article recently reported findings that help us better understand how bats process sound. A team of researchers at Georgetown University Medical Center inserted electrodes into the brains of bats and recorded their neural activity in response to different tones and calls. The researchers concluded that neurons in a bat’s brain work to amplify important sounds and diminish irrelevant ones. The team’s findings were presented at the Society for Neuroscience, an annual conference that took place last week.

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13 years ago

I didn’t realise bats contributed to the ecosystem so much. It’s definitely a bonus if they help reduce the use of pesticides etc. It’s a shame to read some kinds of bats are on the verge of extinction, I had no idea it had gotten to that stage for some.