Estacion Las Tortugas
What is a Reptile?:
Reptiles are a diverse group that include such animals as lizards, snakes, crocodilians, the legendary dinosaurs and turtles. Sea turtles are unique in that the are marine reptiles.
Several things distinguish reptiles from other animals:
Reptiles Do NOT have fur. Rather than having fur reptiles have skin that is tough and covered with waterproof scales.The scales of a reptile are made from keratin; the same substance that makes nails, feathers, hair, and horns of other animals. The thick scaly skin of reptiles prevents their skin from dehydrating easily.
All reptiles have LUNGS to BREATHE AIR.
All reptiles reproduce with INTERNAL FERTILIZATION. Internal fertilization means that the eggs of reptiles are fertilized with the females body before she lays them. This makes reptiles different from amphibians, which lay eggs that are fertilized by the male after being laid by the female.
Reptiles were the first to evolve amniotic eggs that could be laid on land. Amniotic eggs have a tough outer shell and membranes to protect the embryo from drying out. Amniotic eggs can be hard and brittle like those of birds or they can be soft and leathery, like those of snakes, lizards and turtles. The yolk of the egg, the yellow part with which we are familiar, is used by developing embryo as a food source that is high in protein and fat.
Leatherback turtles on average lay about 70 to 80 yolked and 20 to 30 unyolked eggs. Yolked eggs are perfectly round and measure approximately 2 inches (5 cm) in diameter. The yolked eggs are those that will develop into hatchlings. Yolkless eggs will not develop into hatchlings and are often misshapen.
Sea turtles are magnificent reptiles perfectly adapted for ocean life. They evolved from land turtles and still share some important features with their distant cousins. Although they live in the ocean, female sea turtles must lay their eggs on land in order for the cycles of life to continue. The amniotic egg (tough outer shell and membranes to protect the developing embryo inside from drying out), which was so important in releasing reptiles from the sea, still binds sea turtles to the land today.
Sea turtles are not just unique because they live in the sea. They differ from both land and freshwater turtles in a number of ways:
one of the most obvious differences is the shape of their bodies. Sea turtles are adapted to life in the sea so they have lighter flatter, more streamlined shells and paddle-like flippers instead of legs.
As adults they are significantly larger than most other kinds of turtles. In fact one of the largest turtles ever to exist was the now extinct sea turtle Archelon.
Sea turtles have also lost the ability to pull their heads and limbs into their shells.
Since turtles first evolved on Earth over 100 species of marine turtle have existed, most of which are now extinct. Today there are only 7 species of sea turtle in the world, all of which are now in danger of extinction to some degree.
The Turtle Shell:
A turtles most distinct feature is it's shell, which encases and protects the turtles body. Most turtle shells have hard shells, but the leatherback sea turtle and certain fresh water species have softer and more flexible shells. Turtle shells can have beautiful markings. Hawksbill turtles are in danger of extinction because of their beautiful shells, which are poached to make jewelry.
Shells are made up of two parts; the part that covers the back is called the carapace, and the part that covers the belly is the plastron. The carapace and the plastron are held together with cartilage.
The carapace and the plastron consist of two separate layers. One layer is the bone layer. The bone layer is made up of flattened bone plates that are part of the skeleton itself. In all species, but the leatherback the bone plates grow between the ribs as the turtle grows. The bone layer cannot be seen by looking at the shell of a living turtle.
The other layer of the shell is made up of the scales; hard plates call scutes, made of keratin. The layer of scutes is what can be seen when looking at the turtle.
Both the bone and the scute plates have the same general pattern in all turtle species, but do not match each other.
Turtles are famous for being slow, but this is not always true. Land turtles do not walk fast due to the positioning of their legs and heavy shells, but sea turtles who have adapted to life in the water seem to fly when underwater, propelling themselves with strong flippers. On land sea turtles use their flippers and hind limbs to push themselves forward.
It is estimated that sea turtles live to be around 60 years or more, although it is not known for certain.
Leatherback Information: Back to Top
Scientific Name: Dermochelys coriacea
Common name: Leatherback sea turtle
Of all the sea turtles the leatherback is one of the most unique and extraordinary! Not only is the leatherback the largest sea turtle, it is also one of the largest reptiles on the planet today. It makes great journeys through extremes of temperature; from shallow tropical seas, to icy water near the poles and the cold, dark depths far below the surface. It is also the only species of sea turtle without a hard shell, having instead a flexible, leathery carapace that gives this remarkable animal its name.
The leatherback has the widest geographical range of any marine reptile. Leatherbacks can be found as far north as Alaska, Newfoundland and the North Sea and as far south as Chile, and the southern tip of New Zealand.
Not much is known of where leatherbacks forage in the world, but they do not appear to have specific feeding grounds like other species of sea turtles. The leatherback feeds on soft-bodied marine invertebrates, especially animals jellies, siphonophores, and tunicates such as salps and pyrosomas. They forage for these animals throughout the water column, from the warm surface to cold, deep waters. Leatherbacks are capable of diving 1000 meters (3300 feet) in search of prey.
Leatherbacks mostly in the tropics, and occasionally in the subtropics of the Pacific, Atlantic, and Indian Oceans. In the Americas they nest along the Pacific coasts of Mexico, Central and South America and throughout the Caribbean from Costa Rica to Colombia, French Guiana, and Surinam. Important nesting sites are located in Costa Rica, Trinidad, French Guiana and Surinam in the west Atlantic and Gabon (West Africa) in the Eastern Atlantic.
Boy or Girl?:
A turtle hatchlings sex is determined by temperature! At cooler temperatures (below 29°C) males develop and at warmer temperatures females develop.
Adult leatherbacks have an average carapace length of 4.3 to 6 feet (1.3 to 1.8 m).
The average leatherback hatchling have an average carapace length of 2.4 inches (60 mm).
The average adult leatherback weigh in at 500 to 1100 lbs (200-500 kg)
Estación Las Tortugas 2006 Data: Back To Top
Figure 1: This graph represents the amount of turtles ariving
on the beach during the years 2003-2006 at Estación Las Tortugas
Figure 2: The data presents the different species that have visited the beach during the 2006
season at Estación Las Tortugas
Figure 3: Percent of turtles that laid eggs each month during the 2006 nesting season
Figure 4: Numbers and data of the nesting beach during the 2006 Leatherback
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