An intersex shark has been found off the coast of Taiwan in a rare discovery.
The Pacific spadenose shark, caught by stunned fisherman in January this year, was just 1.6 feet (0.5 metres) long and weighed 0.4 kg (0.79 lbs).
The predator is one of only a handful of intersex sharks ever found, and the first of its species.
While many fish have the ability to switch genders, sharks develop permanent male or female organs before birth, making intersex specimens a rarity.
Little is known about shark reproduction, but researchers have suggested that intersexuality could explain why some sharks can give birth ‘asexually’.
‘[Sharks] can give birth without mating – like virgin birth. The question is: Why?’ Dr Chris Lowe, a scientist at California State University, Long Beach, told Hakai magazine.
Intersexuality may be related to this ability of some sharks to give birth to a clone, he said.
‘We just don’t know enough about shark biology to be able to answer those questions,’ Dr Lowe added.
The intersex shark was caught in a fishing trawl in the southern Taiwan Strait, and landed at Xiamen, China, in January 2017.
At first it appeared to be a fully grown male, with a developed pair of penis-like appendages called claspers that extend from the pelvic fin.
But a study of the animal’s interns found it had a complete pair of ovotestes – gonads that contain both ovarian and testicular tissue.
This meant that the animal had both the male as well as the female reproductive organs.
Scientists at China’s Xiamen University found that each of the shark’s genitals were fully formed, meaning the animal could have functioned as either sex reproductively.
This makes the find the rarest type of intersexuality in sharks, as most cases have sex organs that are only partially formed.
According to Dr Carl Meyer, a marine biologist at the University of Hawaii, these intersex sharks are ‘extremely rare’.
Dr Meyer told Hakai magazine it is not yet confirmed if intersex sharks can effectively use both the male as well as the female organs for reproduction.
He added that an intersex shark carrying a live embryo in its uterus has never been found by the researchers.
Some have speculated whether the intersex shark was human-caused.
Recent studies have looked at the increasing discovery of intersex characteristics in fish in the US, a phenomenon that could be linked to the presence of estrogen and other hormones in wastewater.
‘Environmental contamination is certainly not the only reason why this might happen every now and then,’ Meyer says.
‘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.’