In a latest research, scientists at China's Xiamen University have found a rare intersex shark that has both male and female sex organs. According to reports, the scientists analysed the shark and discovered that each of its genitals were fully formed, which suggested that the animal could have functioned as either sex reproductively.
The 50-centimetre-lond Pacific spadenose shark, which weighed 0.4 kg, was caught in a fishing trawl off the coast of southern Taiwan in January this year. This latest finding is surely an exceptional discovery as the shark was one of only a handful of intersex sharks ever discovered, and the first of its species.
Initially, the shark looked like an adult male with a pair of fully developed claspers, which are penis-like appendages that extend from the pelvic fin. However, further examination has revealed that the shark also has a complete pair of ovotestes. These are gonads that contain both ovarian and testicular tissue. Thus, the study indicated that the giant fish had both male and female reproductive tracts.
Generally, sharks have sex organs that are only partially formed. But, this one has the rarest type of intersexuality. Although it is very little known about shark reproduction but scientists believe that intersexuality will give a better explanation of why some sharks can give birth "asexually."
"They can give birth without mating—like virgin birth," Chris Lowe, a scientist at California State University, Long Beach, told Hakai magazine. He added that intersexuality could be related to this unique ability.
Meanwhile, a report in the Marine and Coastal Fisheries Journal has revealed that the shark was the first reported case of intersexuality in the genus Scoliodon. It added that the animal was also a rare record of intersexuality in elasmobranchs, a subclass of cartilaginous fish, including the sharks, rays, skates, and sawfish.
Carl Meyer, a marine biologist at the University of Hawaii, said that it still needs to be confirmed whether intersex sharks can use both their male and female organs for reproduction. According to Meyer, an intersex shark carrying a live embryo in its uterus is also yet to be discovered.
However, the exact cause of the shark's intersexuality is still not clear. Some experts have speculated that the rare phenomenon might be caused by human. But, Meyer believed that genetic drivers could play a bigger role in such case.
"Environmental contamination is certainly not the only reason why this might happen every now and then," Meyer said. "Purely genetic drivers could largely determine what happens during reproductive development. There could be a genetic miscoding that ends up with a rare intersex example in a species."