Two-Headed Bull Shark Fetus Discovered by Florida Fisherman

Two-Headed Bull Shark Fetus

photo by Patrick Rice

Back in 2011, a fisherman off the coast of Florida caught a female bull shark and made a remarkable discovery—in the uterus of the shark he found a live two-headed shark fetus. The bizarre creature died shortly thereafter and was eventually delivered to scientists. An article published this month in the Journal of Fish Biology confirms that the fetus is the first case of dicephalia—“two-headedness”—in a bull shark. Dicephalia occurs when twins fail to fully separate during development in the uterus, a condition also known as axial bifurcation. The rare deformity has been observed in a wide variety of animals as well as humans, though the abnormality is often fatal.

Two-Headed Bull Shark Fetus

photo via Journal of Fish Biology / C. M. Wagner et al

via io9