Clash of the fiercest predators as shark eats polar bear
By Daniel Howden
Tuesday, 12 August 2008
The Greenland shark may challenge the polar bear as the Arctic's top
predator
"Global warming may not be the only threat to the polar bear. Scientists are
puzzling over the discovery of the jawbone of a young polar bear in the
stomach of a Greenland shark, a species that thrives in the cold waters of
the far north.
The find suggests that the polar bear may have a serious challenger to its
place at the top of the Arctic food chain. Until now, only killer whales
were thought to offer a threat to Ursus maritimus as the Arctic's top
predator.
Kit Kovacs, a seal expert at the Norwegian Polar Institute in Tromso,
stumbled across the polar bear remains while attempting to find out who or
what was killing large numbers of harbour seals in the Arctic archipelago of
Svalbard.
The Greenland shark, one of two species of sleeper sharks, was the obvious
suspect, she said, so they performed autopsies to see what they had been
eating. That's when they found the polar bear bone. "We were so shocked we
were laughing," Ms Kovacs said.
The prospect of a marine battle between the world's largest land predator
and the Greenland shark which can grow to a length of more than six metres,
is a true clash of the titans. And it is one that is likely to have wildlife
film-makers rushing for the North Pole.
Climate change has been melting polar ice cover and shrinking the natural
habitat for the polar bear, now regarded as an endangered species. With
polar sea ice expected to disappear altogether during the Arctic summer
within a generation there is speculation that the bears may be spending
longer in the water, while hunting or moving between icebergs. This could
make them a potential target for large marine predators. Warmer waters may
also be tempting more and larger sharks further north.
Shark experts were unconvinced and think it more likely that the shark would
have fed on a bear's carcass, rather than killed a live bear, as even a
young animal would be a fierce opponent.
Steve Campana, head of the Canadian shark research laboratory at the
Department of Fisheries and Oceans, said he had not heard of sharks
attacking a bear before. "It sounds like a scavenge," he told Reuters,
adding that it was a "million-dollar question" for researchers as to whether
Greenland sharks were preying on polar bears.
Ms Kovacs continued, however, to stand by her theory. Sleeper sharks, which
are among the longest living of their species, can descend to depths of
2,200 metres, but seal blubber found in their stomachs by researchers
indicates that they are seeking food in shallower waters. "We didn't know
they went to the surface to feed," she said. "We can't say whether or not
the shark took a swimming young bear or ate a carcass."
One clue may come from what the scientists did not find in their examination
of the shark: anthropods, tiny creatures that feast on carcasses, gaining
access through eyes or belly buttons. Scavengers are usually full of
anthropods but none were found in the stomach with the polar bear.
"We don't know how active these sharks are as predators," Ms Kovacs said.
That is the question scientists will seek to answer.
Sleeper sharks are among the most numerous large sharks in the world and are
prolific feeders which have thrived while other shark populations have
plummeted.
What Ms Kovacs and her research team have found suggests that they are also
much more skilled hunters than was previously believed. Although no one has
witnessed a kill, the scientists' findings appear to show that sleeper
sharks can catch live seals, which are fast and agile prey.ball."
The discovery of the polar bear's jawbone is likely to leave scientists
guessing for some time, but Ms Kovacs said: "I won't be going swimming there
again... They are incredibly cryptic, dark sharks, who move slowly and get
in close." "
---------------
Battle for top of the Arctic food chain
Weight: Adults Greenland sharks and mature polar bears weigh in at more than
one tonne. The bears just have the edge.
Age: These sharks are among the oldest on the planet, some living for 200
years. Polar bears rarely live beyond 25.
Range: Polar bears can swim for up to 60 miles in open water. The shark can
descend to depths of 2,200m.
Weapons: The bears' claws are for digging in ice, its teeth are its main
weapon. The shark has rows of sharp upper teeth..."
</>
Greenland sharks have relatively small teeth and they live in extremeley
deep water. They are called benthic sharks because they live on the ocean
floor. The polar bear probably drowned, as a huge number of them are what
with the ice flows melting, and the shark ate the remains.
Paul
> "...incredibly cryptic, dark sharks..." [!!!]
>
>
> http://www.independent.co.uk/environment/nature/clash-of-the-fiercest-predators-as-shark-eats-polar-bear-891512.html
>
> Clash of the fiercest predators as shark eats polar bear
Booyeah.
--
Blinky
Killing all posts from Google Groups
The Usenet Improvement Project: http://improve-usenet.org
Need a new news feed? http://blinkynet.net/comp/newfeed.html
Killjoy :-(
--
Best
Greg
At least he's not the kind of guy that'd throw a polar bear off a train.
He would if he were a U.S. Marine and it was taking a seat he wanted!
Even if I was a Marine on my way home from a 15 month tour - the polar bear
would still look better to me than you.
Paul
And I, for one, wouldn't blame him!
> Blinky the Shark <no....@box.invalid>
> news:pan.2008.08.26...@thurston.blinkynet.net: in
> rec.food.cooking
>
>> Gregory Morrow wrote:
>>
>>> "...incredibly cryptic, dark sharks..." [!!!]
>>>
>>>
>>> http://www.independent.co.uk/environment/nature/clash-of-the-fiercest-
>>> predators-as-shark-eats-polar-bear-891512.html
>>>
>>> Clash of the fiercest predators as shark eats polar bear
>>
>> Booyeah.
>
> How does bear meat taste Blinky? You've already eaten "Charlie the
> Tuna" :)
Like chicken, of course.
> "Gregory Morrow" <FlyPrahaJaka...@flyokayflycsa.cz>
> news:F6GdnSQ0oaQL7S7V...@earthlink.com: in rec.food.cooking
>
> <snipola fo space>
>
> Interesting article. I enjoyed it. Thanks for posting it. AND the
subject
> was marked OT so the Net Nannies shouldn't bitch about it ;)
>
I thought we needed a bit of levity...
:-)
> > Weapons: The bears' claws are for digging in ice, its teeth are its
> > main weapon. The shark has rows of sharp upper teeth..."
>
> Hmmmm... Wonder who in RFC most resembles the bear? We have our own shark
> so we just need to choose the bear ;-)
I can't think of anyone or anything here I'm scared of...except mebbe
cyberstench's day -old tuna breath.
;-)
Now for a "Charlie the Tuna" I'd nominate Steve Wertz...
--
Best
Greg
Anthropods? Tiny little people?
ooh, snap!
blake
> blake murphy wrote:
>
>> On Tue, 26 Aug 2008 07:36:34 -0700, Paul M. Cook wrote:
>> >>
>>> Even if I was a Marine on my way home from a 15 month tour - the polar bear
>>> would still look better to me than you.
>>>
>>> Paul
>>
>> ooh, snap!
>
> Aw, shucks. You guys are embarrassing the polar bear.
>
> http://tinyurl.com/6g9pnv
<snort>
your pal,
blake