Fisherman in the North Sea coast of Netherlands caught a two-headed harbor porpoise for the first time last month. The process of parapagus dicephalous occurs when porpoises have a single body with two fully grown heads. Erwin Kompanje, researcher of the Erasmus MC University Medical Center in Rotterdam said, “The anatomy of cetaceans is strikingly different from terrestrial mammals with adaptations for living in the sea as a mammal. Much is unknown.” “Adding any extra case to the known nine specimens brings more knowledge on this aspect”, he further added. This type of conjoined twins is rarely seen in wild mammals.
Fishers who made the discovery thought it might be illegal to keep such a deceased marine specimen. Hence, they decided to take the photographs for research purpose and toss it back into the ocean. Although researchers could not examine the twins directly still they can find out something important from the photographs. “Conjoined twins in whales and dolphins are very rare. Sadly, the twins died too early after the birth, because their tail was not yet stiffened which is a necessary development for newborn dolphins to be able to swim, says Kompanje.
Other signs of their age included the rostrums which still contained hairs and contained an umbilical opening and had a flat dorsal fin that should have become vertical immediately after entering the ocean water. Partial twinning takes place in two ways: Either it could take place when separate embryonic discs fuse together or when the zygote partially splits during the early development process.
Kompanje concluded saying, “Adding any extra case to the known nine specimens brings more knowledge on this aspect. Normal twins are extremely rare in cetaceans. There is simply not enough room in the body of the female to give room to more than one fetus”, he added.