Day: March 20, 2022

Environmental, General News

England: Super-rare Greenland shark that washed up on UK beach may be at least 100 years old.
© Provided by Live Science The rare Greenland shark being moved after it stranded in Cornwall.

A rare Greenland shark that washed up on a U.K. beach could be at least 100 years old, but experts aren’t sure why it became stranded.

The dead shark was first spotted on the sand in Newlyn Harbour, Cornwall, on the southwest coast of England, on March 13. But before experts could examine it, the tide came in and took the carcass back out to sea, according to Cornwall Wildlife Trust Twitter posts. 

The shark was then rediscovered floating off the coast of Cornwall on March 15 by a recreational boating company called Mermaid Pleasure Trips and was brought back to shore. Greenland sharks are rarely sighted in the U.K., and this is the country’s second recorded Greenland shark stranding.  

“Even though it’s a sad event when these beautiful, spectacular animals do strand on our beaches, it’s such a valuable opportunity for us to study them,” Abby Crosby, a marine conservation officer who manages the marine strandings network at the Cornwall Wildlife Trust, told Live Science. 

Related: The weirdest creatures to wash ashore

Greenland sharks (Somniosus microcephalus) live in the Arctic and North Atlantic oceans up to 8,684 feet (2,647 meters) below the surface, according to the International Union for Conservation of Nature (IUCN). A 2016 study published in the journal Science estimated that these sharks could live at least 272 years, but scientists still have much to learn about the elusive species.

The shark that washed up in Cornwall was a juvenile female that measured 13 feet (4 m) long and weighed 628 pounds (285 kilograms). Although researchers have yet to determine the shark’s age, Greenland sharks typically become sexually mature when they’re around 150 years old, according to the 2016 study. The animals continue to grow as they age, and adults can be up to 24 feet (7.3 m) long, according to the St. Lawrence Shark Observatory (ORS).  

James Barnett, a veterinary pathologist from the Cornwall Marine Pathology Team, carried out a postmortem of the shark on March 16 for the Cetacean Strandings Investigation Programme (CSIP), a national program that partners with Cornwall Wildlife Trust’s Marine Strandings Network. 

“It looked like it probably live-stranded,” Barnett told Live Science. In other words, the shark was still alive when it washed up, and it died on the beach. “It obviously hadn’t eaten for some time,” Barnett said. “The stomach was totally empty.” 

Barnett noted that the shark showed possible signs of septicemia, an infection in the blood, but it’s not yet clear why the shark wasn’t eating and ended up in shallow waters off Cornwall. There are a variety of reasons, including disease, that can explain why marine animals become stranded and die on beaches, but the movement of ocean currents and other marine conditions also play a part in bringing living and dead animals to shore.

“The majority of our strandings are common dolphins and porpoises, and they would have all died within a kilometer [0.6 mile] of our coastline, if that,” Crosby said. Because Greenland sharks usually swim far from the coast, the likelihood of one being swept in by the right current and weather conditions is really rare, she added. 

Barnett said this is the first time a Greenland shark has been given a necropsy in the U.K., to his knowledge. “They are a species that we just don’t encounter,” he said. Samples taken from the shark will help inform Greenland shark research, such as studies investigating their life history and diet, Rob Deaville, project manager for CSIP at the Zoological Society of London, said in a statement.  

Originally published on Live Science.

Regards Mark

Environmental, General News, Uncategorized

So, Why aren’t there polar bears in Antarctica?
© Provided by Live Science Polar bear on melting ice in Svalbard, Norway_Paul Souders via Getty Images

The Arctic and Antarctica, while similar habitats in some ways, are home to very different creatures. Both poles host a variety of seal and whale species, but only the Arctic is home to Earth’s largest bear, the polar bear.

Polar bears (Ursus maritimus) and their tumbly cubs can be found around the Arctic Circle in Alaska, Canada, Greenland (part of Denmark), Norway, Russia and, occasionally, Iceland. A polar bear’s fur is specially suited for temperatures that can dip below minus 22 degrees Fahrenheit (minus 30 degrees Celsius). They live on ice for most of their lives, feeding on fat-rich seals that keep them energized for long periods between meals.

Antarctica also has sea ice, cold temperatures and seals. So why aren’t there any polar bears on the southernmost continent?

The answer has to do with evolution and the geologic history of Earth.

Related: How do emperor penguin dads stop their eggs from freezing?

“Bears are largely a Northern Hemisphere phenomenon,” said Andrew Derocher, a professor of biological sciences at the University of Alberta in Canada who has studied polar bears for nearly 40 years. Aside from the Andean bear (Tremarctos ornatus) of South America, bears appear only in the Northern Hemisphere. There’s no specific reason for this, just that some species evolve in some places and some don’t. “Biogeography is full of oddities,” Derocher said. “Some species made it to new places and some didn’t.”

For polar bears specifically, there was never a time in their evolutionary history when the North and South poles were connected by ice (or land, for that matter). People say polar bears are the “biggest terrestrial carnivore in the world, and yet they’re not a terrestrial species at all,” Derocher told Live Science. The big, white bears live on sea ice for almost their entire lives, only occasionally coming ashore to breed.

Polar bears are, evolutionarily, a relatively young species. They evolved from a common ancestor of the brown bear (Ursus arctos) sometime between 5 million and 500,000 years ago, Derocher said. But even 5 million years ago, the continents were in similar positions to where they are today, so polar bears never got the opportunity to travel from pole to pole. The closest landmass to Antarctica is the southern tip of South America, which includes Chile and Argentina. To get to Antarctica, polar bears would have to cross the treacherous Drake Passage. The area is also known for powerful storms and rough seas as cold water from the south runs into warm water from the north.

But if polar bears got the opportunity, would they survive on the South Pole?

To Derocher, the answer is simple: “They would have so much fun in Antarctica.”

In the Arctic, polar bears feed on seals and the occasional bird or egg. Antarctica is abundant in all three, with six seal species and five penguin species. Plus, none of those animals have evolved to be wary of large, land-roving predators. The Antarctic landscape would be a free-for-all buffet for a polar bear — which is why no one should ever bring polar bears there. Their voracious appetite, combined with the local faunas’ ignorance of large land predators, would likely lead to ecological collapse. It’s probably best for the great white bear to remain in the north.

Originally published on Live Science.

Regards Mark