Meet the Narluga, Hybrid Son of a Narwhal Mom and a Beluga Whale Dad
Its skull sat in a museum collection for decades before new technology unlocked its genetic secrets.
The odd skull had too many teeth for a narwhal, but too few for a beluga.CreditMikkel Høegh Post/Natural History Museum of Denmark.
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By JoAnna Klein
On
a remote island in Disko Bay, Greenland, a scientist in 1990 was
collecting specimens of narwhals, the whales with unicorn-like tusks. He
noticed an unusual skull on a hunter’s roof.
The
teeth were bizarre: The top ones pointed forward. A couple spiraled
out. They looked like a mix of narwhal and beluga, but with too many for
a narwhal, too few for a beluga.
The
hunter told the scientist that the skull had belonged to a strange
animal he’d killed in the late 1980s. He had also killed two other
similarly strange whales the same day. All had beluga-like flippers,
narwhal-like tails and solid gray skin, he said.
Mads Peter Heide-Jørgensen,
the narwhal scientist, convinced the hunter to donate it to the Natural
History Museum of Denmark for analysis. But at the time, he could only
conclude it was a possible hybrid or deformed beluga.
Thirty
years later, he and others have finally cracked this cold case. A
genomic analysis of DNA extracted from the John Doe skull revealed that
it belonged to an adult, first generation son of a narwhal mother and
beluga father. The study, published Thursday in Scientific Reports,
shows how a little DNA can go a long way, that hybridization isn’t that
unusual and that as long as museums keep storing mysterious stuff, the
right technology might one day set their stories free.
“There
are certainly things lying around that can tell us about the natural
world around us and how it shifts and changes,” said Eline Lorenzen, the museum collection curator who first decided to pull the skull off its shelf.
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Because of its teeth, the hybrid probably had a diet more like a walrus or bearded seal than a narwhal or a beluga.CreditEline Lorenzen.
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Her
lab extracted DNA from the dust of its teeth and bones, and compared it
to genomes derived from tissue samples of belugas and narwhals from the
same area. The analysis, conducted by Mikkel Skovrind, a graduate student, revealed it was a male and a 50/50 narwhal and beluga mix. A first generation hybrid — perhaps a narluga?
And
analysis of mitochondrial DNA, which only comes from the mother,
indicated — surprise — she was a narwhal. Generally only male narwhals
have tusks, which may play a role in advertising social dominance and
attracting females, kind of like deer antlers. But this female narwhal
didn’t seem to mind a tuskless beluga.
The
hybrid whale’s combined features are completely weird, Dr. Lorenzen
said. “It’s like if you took 50-percent beluga and 50-percent narwhal
and shoved their teeth in a blender, that’s what would come out.”
That
probably complicated slurping prey like a toothless narwhal or chewing
it like a beluga. Despite that, the large skull indicated he had
survived well into adulthood. Remnants of carbon and nitrogen in his
bones suggested that he had fed on the seafloor, more like a walrus or
bearded seal than a typical monodontidae.
Reproduction
may also have challenged the creature. Many hybrids in nature — think
mules, the offspring of a horse and donkey — are sterile.
A
skull, left, found on an island in Greenland had too many teeth for a
narwhal, but too few for a beluga. Above, an illustration of what the
hybrid creature might have looked like in the deep.CreditMarkus Bühler.
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Others like him probably have existed, but wouldn’t occur frequently, said Randall Reeves,
a marine mammal biologist who has studied the skull, but was not
involved in the recent genomics research. There is no evidence in the
beluga or narwhal genomes of interbreeding in at least a million years.
The
skull came from one of the few places on Earth where narwhals and
belugas are found together during mating season. And despite constant
monitoring of these and other whale populations by experienced hunters,
government agencies and biologists, there are no reports of other
oddballs, not even rumors, Dr. Heide-Jørgensen says.
Still,
the chances that this occurred only once in a million years and they
just happened upon the skull are slim, said Dr. Lorenzen.
Blue whales have recently hybridized with fin whales. And belugas have interacted with and even adopted narwhals.
Humans and Neanderthals, horses and donkeys, polar bears and brown
bears, at least 16 different whales: Genetics are revealing that
hybridization, though rare, may be more common than we think.
For
now, it’s only possible to speculate about the circumstances that led
to the conception of the baby beluga narwhal, perhaps the
cutest-sounding animal that ever existed. But perhaps it’s just a matter
of time before someone unlocks the secrets of other weird whale skulls
that are waiting to be found.
Only
male narwhals have tusks, which may play a role to attract mates, but
the mother of the hybrid mated with a tuskless beluga male anyway. CreditMads Peter Heide-Jørgensen
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