While one thinks of the Cyclops of Greek mythology and Kabandha of Southeast Asian lore, a rare creature, dubbed a "One Eye Anomaly" by National Geographic was discovered in 2011. The "cyclops shark" was discovered by fisherman Enrique Lucero León and was instantly regarded as a cryptid and a hoax. However, after Enrique brought the specimen to National Geographic scientists, it was discovered that although the shark was not some unique species, it was an extremely rare and fascinating case of a shark featuring a congenital defect called cyclopia, which occurs in several animal species (including humans).
The captured 22-inch-long (56-centimeter-long) dusky shark fetus has a single eye at the front of its head—the hallmark of the disease. Most fetuses of any organism with cyclopia are stillborn, and in the rare case that a living baby is born with cyclopia, the child usually dies shortly thereafter. This is due to a number of additional problems that the fatal congenital disorder causes with other internal organs, including the fact that the respiratory system does not fully develop in fetuses with cyclopia.
Earlier this year fisher Enrique Lucero León legally caught a pregnant dusky shark (Carharhinus Obscurus) near Cerralvo Island in the Gulf of California. When León cut open his catch, he found the odd-looking male embryo along with its nine normal siblings. "He said, That's incredible—wow," said biologist Felipe Galván-Magaña, of the Interdisciplinary Center of Marine Sciences in La Paz, Mexico.
Once Galván-Magaña and colleague Marcela Bejarano-Álvarez heard about the discovery—which was put on Facebook—the team got León's permission to borrow the shark for research. The scientists then x-rayed the fetus and reviewed previous research on cyclopia in other species to confirm that the find did indeed have the congenital defect.
Sharks exhibiting cyclopia have been documented by scientists a few times before, although only as embryos, said Jim Gelsleichter, a shark biologist at the University of North Florida in Jacksonville. The fact that none have been caught outside the womb suggests that like other species, sharks exhibiting the defect are either stillborn or don't survive long in the wild.
Although the creature is unfortunately not a rare and unique species of shark, it is a rare and unique example of one of the rarest and least understood congenital conditions in animals.