Long in the tooth: the Greenland shark
may live four centuries
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[August 12, 2016]
By Will Dunham
WASHINGTON (Reuters) - The Greenland shark,
a big and slow-moving deep-ocean predator that prowls the frigid waters
of the Arctic and North Atlantic, can claim the distinction of being the
planet's longest-living vertebrate, with a lifespan perhaps reaching
about 400 years.
Its extremely sluggish growth rate, about four-tenths of a inch (1 cm)
per year, had already tipped off scientists that it lived a very long
time, and research published on Thursday calculated the Greenland
shark's lifespan for the first time.
Danish marine biologist Julius Nielsen said radiocarbon dating that
analyzed the shark's eye lens found that the oldest of 28 sharks studied
was likely about 392 years old, with 95 percent certainty of an age
range between 272 and 512 years.
Females astoundingly did not reach sexual maturation until they were at
least 134 years old, Nielsen said.
The Greenland shark, up to about 18 feet (5.5 meters) long, is among the
largest carnivorous sharks.
Nielsen, a University of Copenhagen doctoral student who led the study
published in the journal Science, said the findings should bring this
shark much-deserved respect.
"This species is completely overlooked, and only a few scientists in the
world are working with this species," Nielsen said.
"Our findings show that even though the uncertainty is great that they
should be considered the oldest vertebrate animal in the world," Nielsen
Nielsen said the vertebrate with the longest-known lifespan until now
was the bowhead whale, topping 200 years.
Greenland sharks have a plump elongated body, round nose, relatively
small dorsal fin, sandpaper-like skin and gray or blackish-brown
coloration. They are slow swimmers and are nearly blind, but are capable
hunters, eating fish, marine mammals and carrion.
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A Greenland shark is seen on the research vessel Pamiut in southwest
Greenland, in this undated handout picture from Julius Nielsen.
Julius Nielsen/Handout via Reuters
They are known to be relatively abundant throughout the North
Atlantic and Arctic, particularly from eastern Canada to western
Russia. They occasionally are spotted by deep-sea robotic submarines
at latitudes further south, such as in the Gulf of Mexico. They have
been observed in depths down to 1.4 miles (2.2 km).
"They may widely inhabit the deep sea, potentially living anywhere
water temperatures are below about 5 Celsius (41 degrees
Fahrenheit)," said Australian Institute of Marine Science marine
biologist Aaron MacNeil, who was not involved in the study.
MacNeil said the study did an admirable job of tackling a difficult
matter but questioned an element of the dating analysis and said the
estimate of a roughly 392-year-old shark "seems high to me."
(Reporting by Will Dunham; Editing by Sandra Maler)
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