In a rare discovery, a shark off the coast of Taiwan was found to have a fully developed set of male and female reproductive organs.
Though many fish have the ability to change their sexes for convenience of reproduction, the ability is very rare in sharks, which develop either male or female organs before birth.
The intersex Pacific spadenose shark caught in southern Taiwan Strait in January this year was just half a meter long and weighed 0.79 pounds. The animal is one of only a handful of such sharks ever documented, and the first of its species.
The shark when caught looked like a properly grown up male shark. It was fully developed with a pair of calcified claspers — penis-like appendages that extend from the pelvic fin.
When the shark was examined internally, however, it was found to have 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.
A thorough examination by scientists at Xiamen University, China, showed that uncovered viable germ cells of both sexes, meaning it could have potentially functioned as either sex reproductively.
According to a report in the Marine and Coastal Fisheries Journal, this shark was the first case of intersexuality in the Scoliodon genus. The report also confirmed that it was the rarest case of intersexuality in sharks.
The analysis report showed the male reproductive tracts in this shark had epididymides, coiled ductus deferens, and seminal vesicles.
All the reproductive organs measured normal just as in any adult male shark. The female reproductive system consisted of the tract with a heart-shaped oviducal gland and widened uterus on the left side and the oviduct in the right side was broken. However, these also appeared to be like those in a mature female shark.
According to a marine biologists at the University of Hawaii, Carl Meyer, these intersex sharks are extremely rare. Meyer said, “I’ve caught literally thousands of sharks myself, and I’ve never seen one.”
Meyer claimed that it is not yet confirmed if the intersex sharks can effectively use both the male as well as the female organs for reproduction. Meyer also claimed that an intersex shark carrying a live embryo in its uterus has never been detected by the researchers. There have been no documents of an intersex shark impregnating a female in captivity.
Chris Lowe, a marine biologist at California State University, Long Beach, claimed that information regarding shark reproduction is scarce.
Lowe told the Hakai Magazine, “They can give birth without mating – like virgin birth. The question is: why?” He added, “We just don’t know enough about shark biology to be able to answer those questions,” suggesting that intersexuality possibly lets some sharks to give birth to a clone.