On May 2017, a two-headed harbor porpoise was caught and recorded for the first time.
Dutch fishermen accidentally had it as a bycatch in the North Sea off the coast of the Netherlands. But fearing that obtaining the porpoise would be illegal, they returned it back to the ocean. They, however, were able to take photos of it and then alerted the researchers immediately.
There has actually been little evidence about two-headed cetaceans in scientific literature, which means this unusual catch is of importance to understanding marine life.
"Descriptions of conjoined twins in whales and dolphins are extremely rare. We were aware of only nine [other] published cases," says Erwin Kompanje from the National History Museum Rotterdam and co-author of the study
Although the researchers can't physically examine the deceased marine mammal, the pictures alone can provide ample details. For one, researchers definitively know that it's a male newborn. They also know that the creature died shortly after birth based from its dorsal fins that were specifically not erected, pliable and floppy. Its umbilicus is even open and the top of its heads still have hairs. This porpoise is a symmetrical conjoined twin, where the zygote partially splits from incomplete fission or that two separate embryos fuse together.
“The anatomy of cetaceans is strikingly different from terrestrial mammals with adaptations for living in the sea as a mammal. Much is unknown,” Kompanje told New Scientist
. “Adding any extra case to the known nine specimens brings more knowledge on this aspect.”
There's an approximately 700,000 porpoises around the world. Within the North Sea, about 345,000 of these can be found. Each reproduces one offspring every 1-2 years on average. However, with such huge number, the causes of conjoined twins cases still remains a mystery.
Guess we still have a long way to understanding sea creatures especially cetaceans! Nature, man.