Moles Rely on Stereo Sniffing to Locate Prey [Video]

Common mole, the critter that disrupts gardens, can sniff out its prey using stereo scent, according to a new study.

There has been a long-standing debate whether mammals that can see and hear in stereo have the ability to locate a prey by stereo sniffing. A new study has shown that the common mole (Scalopus aquaticus), found throughout the eastern United States, Canada and Mexico, relies on stereo sniffing to find its food.

Researcher Kenneth Catania, from Vanderbilt University, initially tested the common moles' capability to find prey 10 years ago, in order to compare it with the mammal's cousin - the star-nosed mole - which uses its fleshy tentacles around its nose to detect edible objects as it burrows.

"I expected the common mole, which is virtually blind and doesn't have a very good sense of touch, to be a lot worse than the star-nosed mole. So I was quite surprised when they turned out to be very good at locating prey. At the time, I figured that they must be using their sense of smell, but I didn't pursue the matter," Catania said in a statement.

When Catania again studied the sense of smell in the common mole last year, he made this interesting discovery that the moles use cues from stereo odor to locate food.

For the study, Catania created a semicircular arena with food wells spaced around a 180-degree circle. The mole was placed in the center of the arena. Catania placed food randomly in different wells during various trials. The arena was sealed temporarily so he could detect each time the mole sniffed by the change in air pressure.

"It was amazing. They found the food in less than five seconds and went directly to the right food well almost every time," Catania said. "They have a hyper-sensitive sense of smell."

To further investigate the sniffing ability of the moles, Catania blocked one side of the moles' nostril with a plastic tube. When the left nostril was blocked, the moles were found veering off to the right and when the right nostril was blocked, the moles veered off to the left. They were able to find the prey, but took more time to do so.

Then Catania placed the food in the same position, directly across from the entrance. Moles using both the nostrils went directly to their food. But the moles with one nostril blocked consistently veered off to the opposite side.

In another experiment, Catania inserted small plastic tubes in both of the moles' nostrils and crossed them, so that each nostril sniffed air from the opposite side. The animals sniffed around and frequently could not find the food at all, clearly showing evidence that the moles rely on stereo scent to locate food.

The findings of the study, "Stereo and Serial Sniffing Guide Navigation to an Odor Source in a Mammals", are published in the journal Nature Communications.