Rare two-headed juvenile shark found by Palghar fishermanUpdated: Oct 12, 2020, 00:02 IST
A fisherman from Satpati village in Palghar discovered a baby shark, about six inches in length, with two heads in his by-catch on Friday.
Confused by the genetic anomaly, Nitin Patil took a few pictures and videos of the shark before throwing it back into the sea. When he shared the images with other fishermen, he was told that it was a rare anomaly. “We do not eat such small fish, especially sharks, so I thought it was strange but decided to throw it anyway,” said Patil.
Another fisherman, Umesh Palekar said, “We have never seen anything like this before. We believe one of the larger sharks may have given birth to this double-headed shark baby. We shared the images with researchers from the Indian Council for Agricultural Research - Central Marine Fisheries Research Institute (ICAR-CMFRI), Mumbai.”
CMFRI scientists and other marine biologists confirmed it was a very rare documentation and could be the first along the Maharashtra coastline for a double-headed shark species. “Our records show that double-headed sharks are very rarely reported along the Indian coast. This species appears to be the embryo of the spadenose shark (Scoliodon laticaudus) from the Carcharhinidae family or a sharpnose shark (Rhizoprionodon species). Both are viviparous [birthing live young which have developed inside the body of the parent], and are common in Maharashtra waters,” said Dr Akhilesh KV, scientist, ICAR-CMFRI, Mumbai
Dr Akhilesh said the heads were joined behind the gills and such two-headed sharks were quite rare in the wild. “These are also called dicephaly. This phenomenon is reported in several animal species including sharks, possibly due to mutation or any other embryonic malformation, disorders, and these are very rare reports. Similar cases are reported elsewhere outside the northern Indian Ocean. These materials should be preserved out of scientific interest,” he said.
According to CMFRI records, a similar two-headed milk shark (Rhizoprionodon acutus) was reported from Gujarat in 1964, while a two-headed spadenose shark was reported from Karwar in 1991, and a double-headed cownose ray was reported from Andhra Pradesh in 1984.
In 2008, a fisherman discovered a two-headed blue shark embryo in the Indian Ocean, as reported by National Geographic.
Marine biologist Swapnil Tandel said the recently documented species seemed to be a spadenose shark and could be the first record of this species in a dicephalic condition (double-headed) from along Maharashtra waters. “These finds are so rare that it is difficult to find a cause for the anomaly. Genetic or metabolic disorders, viruses, pollution or overfishing could be the possible reasons. If two-headed fetuses are more prevalent in nature, then overfishing is a strong culprit as it may cause the gene pool to shrink,” he said.
E Vivekanandan, emeritus scientist, ICAR-CMFRI said these species have a very low survival rate. “There are hardly any documentations of this species as adults. This finding is purely an aberration. We cannot attribute it to any exact reason. It is regularly seen for snake species or conjoined or Siamese twins in humans. In maximum cases, they do not survive beyond the juvenile stage, but it definitely opens up an avenue for much needed research.”