First-ever two-headed porpoise accidentally discovered by fishermen

A study published online this week in the Journal of the Natural History Museum Rotterdam details the first ever documented sighting of a two-headed porpoise, but much to the chagrin of the scientifically-minded, the paper’s authors were unable to directly examine the creature.

Why, you ask? Because, as National Geographic reported on Wednesday, the fishermen who accidentally caught the deceased specimen in their beamtrawl net feared that it would be illegal to keep it, so they quickly took a few pictures of it and threw it back into the ocean.

Fortunately, they did get in touch with researchers at the National History Museum Rotterdam, who carefully studied photos of the two-headed harbor porpoise in the hope that they could gain new insight about partial twinning (parapagus dicephalus) in marine life, the Telegraph said.

As study author Erwin Kompanje, curator of mammals at the museum, told the Washington Post, parapagus dicephalus is extremely rare among cetaceans. In fact, only nine confirmed cases have been documented in dolphin, whales and porpoises over the last 20 years, he said. “Even normal twinning is rare; there’s no room in the womb of the mother for harboring more than one baby.”

Specimen was lost to science, likely for good, author said

Despite the fact that they were unable to directly examine the porpoise, they were able to discern from the photographs that the creature was male and a newborn, because it still had tiny hairs on its upper lip that typically fall out after birth, its tail had not yet become still enough to allow it to swim, according to Nat Geo and the Telegraph.

The creature also still contained an umbilical opening and its dorsal fins were not yet erect, the researchers said – further evidence that the creature likely died shortly after birth. In most cases, conjoined twin cetaceans tend to be undeveloped fetuses (as was the case of a specimen caught in a dolphin’s womb in Japan in the 1970s), the Post noted.

However, Kompanje is fairly convinced that this latest specimen was born alive, and that it had died soon thereafter, possibly due to the heart’s inability to pump enough blood to keep both of the heads alive. Unfortunately, any chance to gain additional information through a CT or MRI scan was lost when the fishermen who captured the creature panicked and returned it to the sea.

“The crew of the fishing vessel thought it would be illegal to keep the dead porpoise and they threw the specimen back into the sea. Fortunately, first a series of photographs was taken,” he and his colleagues wrote. “The specimen, however, is lost for science and natural history.”

“They thought it was illegal to collect it. They made four photographs and threw it back into the sea. Back into oblivion,” Kompanje lamented to the Post, adding that he did not expect that there would ever be another chance to study this specimen – or any others like it. “For a cetologist, this a real horror,” he told the newspaper.


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