By Tia Ghose, Senior Writer |
June 15, 2017 07:39am ET
Two-headed conjoined porpoises
were recently hauled up by a fishing boat in the North Sea, not far off the
coast of the Netherlands.
The bizarre-looking
creatures were already dead, and the fishermen, who feared trouble from
the authorities, took photos and then tossed the duo back overboard.
It's not clear exactly why the
porpoises died, but the double-headed creatures likely could not swim, said
Erwin Kompanje, a researcher at the Natural History Museum and the Erasmus MC
University Medical Center in Rotterdam, the Netherlands, who recently wrote up
the case in the June 7 issue of the journal
Deinsea. Another cause may have been their fused hearts, which may
not have worked adequately, Kompanje said.
Conjoined twins
Conjoined
twins are a rarity for humans, but they're also extremely rare for
harbor porpoises (Phocoena phocoena),
Kompanje said. That's because newborn dolphins and
porpoises, which are mammals, need to immediately start swimming on their own
or they drown, Kompanje said.
"Normal twins are extremely
rare in cetaceans, as there is not enough room in the mother's body to have
more than one fetus," Kompanje told Live Science. One case report pegged
the incidence of twinning in cetaceans at less than 1 in 200.
Only one past case of a harbor porpoise bearing
twins has ever been reported. Given the rarity of twinning, it stands to reason
that conjoined twins are even more of an oddity, he added. In the past, only
nine other cases of conjoined twins have been reported in whales or dolphins,
and most of these were described in fetuses pulled from dead pregnant females,
according to the study.
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