Wiggling Whiskers Help Hungry Seals Hunt in the Dark

The answer to how deep-diving seals find their food in black seas may have been under their noses. Researchers have seen this sensory system in the wild for the first time with the help of a group of elephant seals.

Researchers at the University of California, Santa Cruz, and their colleagues recorded more than nine hours of footage of the animals' whisker hairs while they dove. Most similar studies of wild marine mammals only use trackers that measure how far animals travel and how deep they go. Scientists built cameras that were small enough to record seals' deep dives. The first-of-its-kind video footage used in the team's new study is a big step forward in understanding how seals hunt.

Researchers had long suspected that the sensory system was the key to the Seals knack for low-light hunting. In natural conditions, animals will use all of the information from many sensory systems to shape behavior. Taiki Adachi is the lead author of the study. seals use whiskers in the deep ocean

The spot where the whiskers meet the seal is surrounded by nerve endings that are sensitive to small changes in nearby water flow. In the study footage, Adachi and his colleagues saw the seals moving their whiskers back and forth with muscles in their snout, like rats and mice do. The researchers only observed this behavior once the seals were down at their usual hunting depths. The seals kept their whiskers against their heads when they weren't eating. When the animals were ready to eat, the whiskers started to move.

Adachi says it's difficult to think about how seals sense nature with their whiskers. Elephants see the world in a different way than us. Adachi and his team looked at the whiskers and camera footage to see if the seals could see bioluminescent prey. In one out of five hunts, the bright bioluminescent glow only lined up with a successful catch for the seals. A primary role was likely played by the whiskers.

A marine scientist who has conducted many years' worth of experiments monitoring whiskers in captive seals was not involved in the new study. The results are very impressive, and it's a great challenge to do this in the wild. Video of the whiskers alone doesn't necessarily show that they are moving in response to water motion around the seals. Future experiments should measure both the whisker wiggles and the water flow at the same time. The data could be used to show how much seals rely on whiskers.