New research reveals that seals can determine the size of objects with their whiskers.
Using whiskers as an extra sense is common in many mammals such as rats, shrews, and even cats–they use their whiskers to explore their surroundings. According to a new study, seals press their whiskers to objects in order to ‘feel’ the size through contact points on the whiskers. The seals were able to determine the size of an object in less than 0.4 seconds. These findings suggest that seals can tell whether a fish is big enough to be worth chasing.
“The method they use allows them to lightly press their face to the prey and decide whether they like it or they don’t,” explained Dr. Robyn Grant, a professor at Manchester Metropolitan University (MMU). “In the highly competitive environment of the ocean, this speed of decision can be the difference between eating or going hungry, and ultimately between survival or starvation.”
Dr. Grant and colleagues studied two adult harbor seals, Marco and Moe, at the marine science center at the University of Rostock. The researchers put headphones and eye masks on the seals in order to restrict their other senses. They then taught the seals to choose between two different size discs. In order to get a fish reward, Moe had to touch the larger disc and Marco had to touch the smaller disc.
“What was not known was whether it was the number of whiskers or the way the whiskers were positioned which helped them determine size, said Dr. Grant. But, the way they oriented their whiskers suggests that it has to do with the number of whiskers–they can tell how big an object is by the number of whiskers touching that object.
In addition to helping the seals quickly judge the size of a potential meal, it is also likely to help them hunt in water with low visibility.
To learn more:
- Read the full article from MMU: Seals judge size with their whiskers
- Find the study, published in the Journal of Comparative Physiology A, here: Vibrissal touch sensing in the harbor seal (Phoca vitulina): How do seals judge size?
- Check out this one from BBC News: Seals judge size using their whiskers
Copyright © 2013 by Marine Science Today, a publication of Marine Science Today LLC.