TEXTO:
The Greenland shark
They can be as big as great white sharks, but that’s
about as far as the comparison goes. Their maximum
speed is a lethargic 1.7 miles per hour, many are almost
blind, and they are happy to eat rotting carcasses. They
[5] may be common throughout the ocean, but you’ve
probably never heard of them. Meet the Greenland
shark. Looking like nothing so much as a chunk of
weather-beaten rock, Greenland sharks (Somniosus
microcephalus
) can grow up to 7.3 metres (24 feet) long,
[10] making them one of the largest of all fish, and the biggest
in the Arctic. But they prefer to live in deep, cold water,
so humans rarely see them.
Studies in the Arctic have revealed a few snippets
of information about Greenland sharks, and more data
[15] is now starting to come in from elsewhere. It turns out
that Greenland sharks are bizarre, and may be crucially
important for the ocean ecosystem.
Greenland sharks only come close to the surface
in places where the shallow water is frigid enough for
[20] them — primarily in the Arctic. They are most easily
seen around Greenland and Iceland. As a result, they
were long thought of as purely polar animals, as were
the closely-related Pacific sleeper shark and southern
sleeper shark.
[25] But they have been reported on the coasts of
Canada, Portugal, France, Scotland and Scandinavia.
Some researchers think they live in many other areas
too but just haven’t been spotted in them yet. “They may
be everywhere that’s cold enough and deep enough,”
[30] says Aaron MacNeil of the Australian Institute of Marine
Science, in Townsville, Queensland.
The obvious way to see a Greenland shark in the
wild is to dive into the deep sea. For instance, in 2001 a
remotely operated vehicle in the Gulf of Mexico captured
[35] footage of either a Greenland shark or a sleeper shark in
over 2,600 meters (8,530ft) of water. Two years later, a
pilot and a scientist from the Harbor Branch
Oceanographic Institution in Fort Pierce, Florida, became
the first people to come face to face with a Greenland
[40] shark in the deep sea. The shark, which was five meters
(16ft) long, bumped into their submersible vessel 1,000
meters (3,280ft) down in the Gulf of Maine. But hardly
anyone dives that deep. So these rare encounters can’t
tell us how widespread and important the Greenland
[45] sharks are.
The Greenland shark. Disponível em: www.bbc.com/earth/20141028- the-mystery-shark-of-the-arctic. Acesso em: 12 out. 2014.
The only piece of information that does not fit the Greenland sharks is that
