Two-headed olive ridley turtle hatchling

Ostional, Costa Rica. 11/29/05. The night of November 20, a two-headed olive ridley sea turtle hatchling (Lepidochelys olivacea) crawled out of its egg and caught the attention of WWF, the global conservation organization. Deformations of this sort can be associated with contaminants, increased temperatures possibly resulting from climate change, or other causes.

Olive ridleys are endangered. Ostional, a village on the Pacific coast of Costa Rica, is one of three places in the world where “arribadas”, synchronized emergences of thousands of nesting female turtles, can still be seen.

“The specific cause of this case of bicephalism is not known. But, increased temperatures as an outcome of climate change cause drastic modifications to the incubation environment in sea turtle nests. Similarly, industrial and agricultural contaminants dumped into river channels reach the sea and become incorporated into the food chains, where they can affect sea turtles,” explained Carlos Drews, WWF Regional Coordinator for Marine Turtles, after photographing and filming the unusual hatchling.

Both heads and the four extremities looked perfectly well formed and capable of the typical range of movements.

The carapace, however, had a notorious malformation along the center: the dorsal scutes erupted upward and lost the usual shape and contiguous pattern. “This is something that no one here has seen in more than 50 years of working with sea turtles,” said Melvin and Olger Chavarría, owners of a local lodge who found the hatchling.

The two-headed hatchling was born in good health: both heads were emerging above the water surface to breathe. The hatchling was kept for one week in an aquarium and released on the night of the 27th November into a sea of uncertainties.

“We have no idea of the condition of the internal organs of this hatchling, so we cannot estimate its probability of survival. Plus, severe obstacles await it in the sea, mainly fishing nets and fishhooks,” added Drews.

He noted that each head seemed to control the movements of the front flipper adjacent to it. Thus, breathing was not synchronous, but rather the result of each head seeking the surface independently with one-flipper strokes. On land, however, the hatchling was able to move in one direction in what looked like a well-coordinated effort of both front flippers to propel the body forward simultaneously.

WWF believes that a successful turtle conservation program requires scientific backing at international, national and community scales to obtain more information about the number of turtles that are nesting on the beaches, whether the species and their food sources are increasing or declining, on their relationships with other living organisms, and on the presence of anomalies and malformations that may serve as early warning signals for identifying threats.

“Factors that affect sea turtle embryonic development must be investigated, because the species can serve as indicators for recognizing the impacts of climatic alterations or pesticides and agrochemicals on coastal and marine ecosystems. The alarming condition of sea turtles today points to an urgent need to improve our relationship with the oceans,” concluded WWF’s expert.