Two-Headed Sharks Keep Popping Up—No One Knows Why
Scientists are discovering more mutated fish, possibly due to genetic abnormalities from overfishing.
Two-headed sharks may sound like a figment of the big screen, but they exist—and more are turning up worldwide, scientists say.
A few years ago off Florida, fishermen hauled in a bull shark whose uterus contained a two-headed fetus. In 2008, another fisherman discovered a two-headed blue shark embryo in the Indian Ocean.
Now, Spanish researchers have identified an embryo of an Atlantic sawtail catshark with two heads, according to a new study in the Journal of Fish Biology. While raising sharks for human-health research in the laboratory, a team noticed the unusual embryo in a see-through shark egg.
The catshark embyro was not your average two-headed beast—it's the first such specimen known from an oviparous shark species, or
