Squid and fish use flashes of light to disorient hungry elephant seals

After spending weeks nursing their pups on the beaches of Antarctic islands, elephant seal moms dive back into the Southern Ocean starving for a fresh meal.

Until now, scientists weren't sure how the hungry, deep-diving predators found their prey in the dark and whether or not the elephants seal mothers face much resistance from bioluminescent species.

New research suggests securing that first meal isn't easy. That's because bioluminescent prey like squid and fish found in the inky depths of the Southern Ocean use light to protect themselves two ways. The sea creatures use dim light to camouflage themselves from below and bright flashes to throw would-be predators off their trail.

To get a better sense of the game of cat-and-mouse played by elephant seals and bioluminescent prey, scientists developed special tags designed to both track the movements of elephant seals and register flashes of light.

Researchers attached the novel tags to a group of elephants seals along the coast of Antarctica's Kerguelen Islands. The data showed the great lengths the seals travel to find food and the techniques squid and fish use to avoid predation.

Researchers analyzed thousands of miles and GPS tracking data and thousands of bioluminescent flashese recorded by the tags.

"The prey always emits a flash the second the seal launches an attack, which suggests that the flash is a defensive reaction when the prey realizes it is being attacked," Pauline Goulet, researcher at the University of St. Andrews, said in a news release.

The data -- published this week in the Journal of Experimental Biology -- showed seals were quick to capture fish that failed to produce a flash of light, but were often thwarted by species that offered a briefly blinding flash.

Observations suggest the flashing trick doesn't always. At least one seal used a twitch of its head to trick prey into producing a defensive flash, revealing their location.

During follow-up studies, scientists hope to studying the details of different flashes so to track the squid and fish species preferred by elephant seal moms.

Related Links
Water News - Science, Technology and Politics

Tweet

Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

DNA in fish feces reveals which species eat crown-of-thorns starfish
Washington DC (UPI) May 18, 2020
Genetic analysis of fish feces suggests crown-of-thorns starfish are a surprisingly popular menu item. According to the findings, published Monday in the journal Scientific Reports, several popular commercial fish species, found in both aquariums and the grocery store, snack on the reef-eating starfish. The crown-of-thorns starfish isn't invasive, but it is a pest. Since 1962, the species' numbers have exploded three times, decimating coral reefs. Ecologists and conservationists have lon ... read more