The first ancestors of these reptiles appeared more than 100 years ago as terrestrial turtles(suborder Cryptodira), who little by little adventured into the sea. In order to adapt to their new environment their extremities developed fins and their bodies flattened out forming an somewhat hydrodynamic shape, thus enabling them to cover tremendous distances in the open oceans throughout the world.
Currently, marine turtles form two distinct families, seven species and one subspecie. The family Chelonidae includes Caretta caretta (loggerhead), Eretmochelys imbricata (hawksbill), Lepidochelys olivacea (olive ridley), Chelonia mydas (green and white), Chelonia mydas agassizii (black), Natator depressus (flatback), and Lepidochelys kempii (Olvide kempii o lora); while the second family Dermochelyidae contains only one living specie, the Dermochelys coriacea (leatherback). All species of marine turtles can be found on the "In Danger Of Extinction" list, clearly demonstrating the critical situation which now confronts them.
Within the province of Bocas del Toro there
exists a wide variety of habitats including
lagoons, mangroves, estuaries, coral reefs,
ocean coastal waters, and sandy beaches, all
of which are important ecosystems that serve
as a source of food, migration, and nesting
for the Leatherback, Hawksbill, Green and
Loggerhead turtles.
Leatherback Turtle(Dermochelys coriacea)
This particular specie is the most important
of all those found in the Bocas del Toro province,
due to its robust reproductive cycle, which
can be observed during the months between
March and June along the beaches of Chiriqui,
Changuinola, San-San, Bluff and Bastimentos.
It is the largest of all marine turtles, with
a mature female averaging 152 cm in length
and weighting nearly one half a ton. Females
lays their eggs approximately 9 times during
the 4 month gestation period, with intervals
of 10 days. While nesting, they deposit an
average of 82 productive eggs and 30 non-productive
eggs. The incubation period, normally determined
by the climate, is between 50-70 days, and
its diet consists primarily of zooplanton
and jellyfish.
The Hawksbill Turtle(Eretmochelys imbricata)
Several different studies conducted by the
Meylan doctors have led to the conclusion
that this particular specie has nesting areas,
feeding, migratory routes, and habitats for
it's development within the Bocas del Toro
province. During the mating season one can
observe males and females along the coastal
areas, however, the most important mating
periods are between the months of May and
September along isolated beaches and in areas
of considerable vegetation. The beaches of
Chiriqui, Bastimentos and Zapatilla Cay are
the areas most frequently visited by Hawksbill
turtles. Between the months of September and
September and March one can observe juveniles
among the marine plants (Sargassum sp. & Syringodium
sp.)
The Green Turtle (Chelonia mydas)
This particular specie is a herbivore and
can be found primarily among the marine grasslands,
often referred to as "turtle grass" (Thalassia
testudinum). It's rounded, flat snout and
serrated jawbone allows for it to feed on
these particular grasses. A chestnut colored
shell, ranging from clear to dark, measures
between 90-110 cm in length; the shell can
also be an olive green color. Adults weigh
less than 230 kg.
In Bocas del Toro there exists only sporadic nesting activity along the beaches of Bluff, Bastimentos and Changuinola, with the most important nesting area found along Costa Rica's Atlantic coast, more specifically the beaches of Tortuguero. Within Chiriqui Lagoon one can find juvenile and sub-adult Green Turtles.
The Green Turtle has been known to cover thousands of kilometers in open ocean during the feeding, mating and nesting cycles.
Loggerhead Turtle (Caretta caretta)
Known for it's large wide head and small rear
fins, the Loggerhead has a chestnut gold colored
shell, that sometimes exhibits a reddish color,
which is often accompanied by encrusted crustaceans.
A strong jawbone permits it to eat conch,
clams, and crabs, however, it is also known
to eat jellyfish and seaweed. Adults can reach
up to 120 cm and weigh up to 200 kg.
This specie is found in Panamanian waters all year long, however, it is not unknown which beaches in the Bocas del Toro area serve as important nesting sites. Generally speaking, adults can be observed among the coral reefs while feeding.
Reproduction
Female turtles lay their eggs during evening
hours in appropriate places, but generally
above the high tide mark. The majority spawn
along sandy beaches near deep water, with
no parental assistance provided. Upon visiting
the beach area, females first prepare the
nesting area with their anterior fins, and
later, utilizing their rear fins, excavate
a hole between 45-80 cm deep (this depends
on the species), where they lay their eggs.
Afterwards, they cover the eggs with sand
using their front and back fins in an attempt
to conceal them. The sun's heat incubates
the eggs, and the nest's temperature determines
the sex of the turtle (temperatures higher
than 29C produce females while lower temperatures
produce males).
The hatchlings emerge from the nest more or
less at the same time, which assists them
during their departure. To better protect
themselves from the heat and predators, which
include birds, crabs and small marine life,
they depart from their nests in the late afternoon
or early evening hours. Upon reaching the
water, the hatchlings immediately head for
deep water, where they have better chances
for survival. Adult marine turtles, both male
and female, are constantly migrating, and
often travel far from their feeding areas
in order to reproduce. Mating normally takes
place during migration or along coastal waters
near the nesting beach.
In Conclusion
Marine turtles, like all reptiles, require
air and must surface regularly in order to
breath. In addition, their life cycle is linked
to the beach from which they spawn and where
they begin their life cycle. It is unclear
as to just how turtles live in the open ocean
under natural conditions, however, it is believed
that they can reach 75 years of age or more,
and that it takes nearly 30 years before they
become sexually mature.
Due to their long life span, migratory habits and presence in several different provinces, marine turtles are of great national importance. For this reason, it is paramount that protective and conservation measures be implemented along the nesting beaches for turtles during their reproduction process. Moreover, in order to adequately introduce a conservation program for marine turtles in the Caribbean Sea, the countries of Panama, Costa Rica and Nicaragua must collaborate their efforts effectively. Without such an effort, the entire region will lose this precious marine resource.
Written by Cristina Ordoñez Espinosa
(Institute for Tropical Ecology and Conservation
- ITEC)
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