Sharks with two heads began to come across in the ocean. Scientists can not yet determine the causes of this phenomenon.
The two-headed shark may seem like a character in a science fiction film, but now it is a reality that is increasingly encountered. A significant part of scientists believe that the cause of such mutations are genetic abnormalities caused by depletion of fish stocks and, possibly, environmental pollution.Scientists have discovered a two-headed cat shark embryo.
In general, among the causes of such deviations there are quite a few factors, including viral infections and a terrifying pace in the reduction of the gene pool, which ultimately leads to inbreeding and an increase in genetic abnormalities.
It all started a few years ago, when off the coast of Florida, fishermen pulled a bull shark out of the water, in whose uterus there was a two-headed fetus. And in 2008, already in the Indian Ocean, another fisherman discovered an embryo of a two-headed blue shark. In 2011, researchers working on the Siamese twin phenomenon discovered several blue sharks with double-headed embryos in the northwestern waters of Mexico and in the Gulf of California. It was these sharks that produced the maximum number of registered double-headed embryos, which is explained by their ability to give birth to a huge - up to 50 - number of cubs at a time.Double-headed sharks have recently come across more and more.
Now, researchers from Spain have identified the two-headed embryo of a rare cat shark (Galeus atlanticus). Scientists from the University of Malaga worked with nearly 800 embryos of varieties of this shark, studying the work of their cardiovascular system. However, in the process, they discovered a strange embryo with two heads.The cause of such mutations may be depletion of fish stocks, environmental pollution, a decrease in the number of sharks themselves and viral diseases.
Each head had a mouth, two eyes, five branchial openings on each side, a chord and a brain. In this case, both heads passed into one body, which was completely normal and had all the signs of a normal animal. However, the internal structure was no less surprising than two heads - in the body there were two liver, two esophagus and two hearts, and there were also two stomachs, although all this was in one body.The uniqueness of the two-headed embryo is that it belongs to an egg-laying shark.
According to researchers, the embryo is a two-headed fused twin, which periodically occurs in almost all vertebrates. Scientists who have encountered this phenomenon believe that if the discovered embryo happened to be born, it would hardly be able to survive, since with such physical parameters it would not be able to swim quickly and hunt successfully.
The uniqueness of this find is that this is the first time that a two-headed embryo was discovered in an oviparous shark. Perhaps this circumstance explains why such samples almost did not fall into people's hands, unlike embryos of viviparous sharks. At the same time, according to scientists, it is hardly possible to fully investigate this phenomenon, since such findings are always random and it is not possible to collect enough material for research.