29/11/2005
- 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. |