Intersex fish are more common that you think. Their sex can change depending on what gender they need to be for reproduction.
Finding sharks that are intersex is more rare. There have only been a small number of cases. Fishermen in the southern Taiwan Strait discovered a shark with both sets of female and male genitalia.
One Of A Kind
Off the coast of Taiwan, fishermen found that in their fishing trawl, they had captured a shark that had both sets of female and male genitalia. Both sets of reproductive organs were fully developed.
The Pacific spadenose shark is one of a handful of intersex sharks that have been discovered in the world. It is also the first of its species to be intersex.
The shark was then examined in Xiamen, China, where it was studied by scientists at Xiamen University.
When first examined, it looked to be a male shark with claspers. Claspers are two penis-like organs that are found in cartilaginous fish, sharks, rays, and skates. After further examination, the shark had both internal reproductive tracts, along with ovotestes. These ovotestes are gonads with both ovaries and testes.
Shark's sexual organs are paired up — they'll either have claspers with a pair of testes or uteri with a pairs of ovaries. When they're usually discovered to be intersex, one side has more developed male organs while the other has more developed female organs
Scientists found that the shark could use both of its female and male genitalia to reproduce. They've, however, never observed an intersex shark carry a live embryo or impregnate another shark.
There is also worry that this may be a human-caused phenomenon. Recent studies have found that there in an increasing number of intersex fish found in lakes in the United States. This is linked to hormones from birth control pills being found in the wastewater.
"Environmental contamination is certainly not the only reason why this might happen every now and then," said marine biologist Carl Meyer from the University of Hawai'i. "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."
There's still much that is unknown to scientists about shark reproduction. Elasmobranch, a subclass of cartilaginous fish, has the ability to reproduce asexually.
"They can give birth without mating — like virgin birth, The question is: why?" said marine biologist Chris Lowe to Hakai. "We just don't know enough about shark biology to be able to answer those questions."