A bizarre-looking two-headed porpoise has been discovered by the fishermen off the coast of the Netherlands. The fishermen were shocked to see the creature, which was later identified as a conjoined harbour porpoises (Phocoena phocoena).
The porpoise has two fully grown heads and a single body and this has been termed a case of partial twinning, or parapagus dicephalus.
Researchers have called the creature extremely rare as the male porpoises are only the 10th known case of conjoined twins in cetaceans. This group of animals also includes whales and dolphins.
“The anatomy of cetaceans is strikingly different from terrestrial mammals with adaptations for living in the sea as a mammal. Much is unknown,” says Erwin Kompanje at the Erasmus MC University Medical Center in Rotterdam, and one of the authors of the paper describing the find. “Adding any extra case to the known nine specimens brings more knowledge on this aspect.”
The porpoise was probably already dead when it was caught. The fishermen soon returned the twins to the ocean. However, they clicked a series of pictures of the creature for research. They returned it to the ocean as they believed it would be illegal to keep it.
According to Kompanje, researchers will not be able to directly examine the porpoise as it has now been lost in the ocean, however, the pictures can help them.
Kompanje says the porpoise died shortly after death as its tail had not stiffened, a necessary factor for newborn dolphins to be able to swim.
A flat dorsal fin was another sign of their age and it should’ve been turned vertical soon after entering the ocean water. Also, the hair on the creatures upper lip should fall out shortly after birth.
“Normal twins are extremely rare in cetaceans,” adds Kompanje. “There is simply not enough room in the body of the female to give room to more than one fetus.”
Most conjoined twins may go unnoticed by science due to the vast size of our oceans.
“Conjoined twins will be more common than the 10 cases we know at this moment, but we are unaware of them because they are born at sea and are never found,” says Kompanje.