Usually two-headed animals will appear in myths, movies or through rumors after nuclear disasters like Chernobyl, but when they appear in real life, they are always called monsters. However, it is a fact that more and more two-headed sharks are being born around the world, while scientists at this time are only at the level of guessing the reason for this phenomenon.
This puzzling phenomenon began in 2008, when a fisherman caught a two-headed blue shark embryo off the coast of Australia. In 2013, a group of fishermen in Florida, USA, discovered a 2-headed fetus in the womb of a bull shark they caught.
In 2008, a fisherman named Christopher Johnston was fishing in the Indian Ocean about 200 to 900 miles from Western Australia when, while pulling his net, he spotted a pregnant blue shark.
When he opened the belly of that shark, he discovered that there was a two-headed fetus inside. He decided to take and share the above photo after scientists confirmed the discovery of a strange two-headed bull shark fetus, off the coast of Mexico.
A few years later, in 2013 – about a year after the oil spill on the Deepwater horizon. A group of Florida fishermen caught a large cow shark in the Gulf of Mexico, and when it was opened up, it was found that its uterus contained a two-headed fetus. Before that, sharks giving birth to two-headed fetuses have occurred in other shark species, and this is the first record of this phenomenon observed in a bull shark.
To date, the blue shark is the species with the most two-headed offspring because the mother shark can carry 50 babies at a time in her belly.
In 2011, an entire study was written about two-headed blue sharks caught in the Gulf of California and off the coast of Mexico. Because it is the shark that carries the most offspring in a single breeding season – up to 50 young per birth – it also has the highest rate of two-headed embryos of any shark species. exist on our planet.
Most recently, Spanish researchers discovered a two-headed embryo in the egg of an Atlantic sawtail cat shark in a laboratory study – the first time the anomaly has been observed. observed in an oviparous species. Valentín Sans-Coma, who led the study, believes that a genetic disorder is at work in the sharks, and that it may be responsible for the deformity, even though the eggs are not infected. , chemicals or radiation.
In wild sharks, there can be many reasons for the mass emergence of two-headed embryos such as viruses, metabolic disorders, pollution and inbreeding from overfishing can all play a role. some game.
MRI scan of a two-headed bull shark. Some researchers suggest that overfishing may be to blame for the growing number of two-headed sharks. As populations decline, their gene pool shrinks, making room for more inbreeding and an increasing number of birth defects.
In another recent study, Nicolas Ehemann, an MA student at the National Institute of Technology in Mexico, examined the two-headed fetus of a dog shark and a blue shark, two-headed specimens. first appeared in the Caribbean. He concluded that the cause of this double-headed deformity was most likely human overfishing and led to a decline in genetic diversity in sharks.
On the other hand, Galván-Magaña, the author of the 2011 study, believes that sharks actually have a lot of different embryonic mutations, but it seems that the press is only reporting on the phenomenon of two-headed sharks. .
He says he has seen a lot of strange things – for example, a few years ago in Mexico, a cyclops shark was caught with a single eye, the special thing is that this eye can still work perfectly perfect. However, such disorders can occur in all animals, including humans.
Ehemann also admits that shark abnormalities are not easy to study because so far we have collected relatively few specimens. “It doesn’t matter if you cast your net a few times and catch a few two-headed sharks. It’s just a coincidence,” the researcher said. “I wanted to study these things, but it’s not like you cast a net and catch two-headed sharks so often,” he said. “It was random.”
We can only hope that such occurrences are truly random and that there is no underlying pattern (and cause) of the increase in sightings.
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