According to a report in the Journal of Fish Biology, American marine biologists discovered the first ever two-headed bull shark last year in the Gulf of Mexico. Different from conjoined twins whose bodies are connected in utero, the phenomenon known as dicephalia has previously been observed in other marine species such as blue or tope sharks.
“This is certainly one of those interesting and rarely detected phenomena,” said report co-author Michael Wagner, assistant professor of fisheries and wildlife at Michigan State University. “It’s good that we have this documented as part of the world’s natural history, but we’d certainly have to find many more before we could draw any conclusions about what caused this.”
Creatures with dicephalia often die quickly after birth, making their discovery extremely rare. The researchers were fortunate that a fisherman found the two-headed shark after opening the uterus of an adult shark he had caught.
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