A wild polar bear has just broken the record for the longest underwater dive made by a member of his species, Ursus maritimus. It lasted for 3 minutes and 10 seconds! That’s about 2 minutes longer than the previous record. These observations were reported in the August issue of Polar Biology.
The adult male made this epic dive during an “aquatic stalk” of three bearded seals (Erignathus barbatus) who were lying several meters from each other at the edge of an ice floe in a Norwegian archipelago called Svalbard. In those 3 minutes and 10 seconds, the bear swam 45 to 50 meters without surfacing to breathe – or even to reorient himself to the seals’ locations, according to a duo led by University of Alberta’s Ian Stirling. But, unfortunately for the bear, the seals got away. The submerged hunter exploded out of the water, Live Science explains, and propelled itself halfway onto the floating ice, right in front of where one seal was resting.
Polar bears split off from brown bears (Ursus arctos) about 400,000 to 500,000 years ago, which is pretty recent in evolutionary terms. Their ability to hold their breath for so long may be an indication of when the species began to develop major adaptations for living and hunting in this marine environment. Until now, the longest recorded dive, which was for kelp, lasted 1 minute and 12 seconds.
This dive’s duration may be nearing the maximum capability for polar bears. But while this is the longest dive reported to date, we don’t actually know what their maximum dive duration is. Opportunities for documenting undisturbed bears are very rare.
Unfortunately, increased diving abilities can’t evolve fast enough to make up for the increasing difficulty of hunting seals, the team says. The availability of sea ice during the open-water times of the year is rapidly declining. In fact, we recently learned that polar bears who enter a low-energy mode called “walking hibernation” during times of food deprivation aren’t saving that much energy – certainly not enough to compensate for seal shortages during the summertime melt. Although, as it turns out, polar bears are now also killing and eating white-beaked dolphins for the first time, and some populations are moving into Arctic regions that are likely to retain sea ice for longer into the future.
[Via Live Science]
2