Green turtle

Scientific name: Chelonia mydas
Phylum Reptilia

Distribution: Extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans. Found in tropical and temperate reefs.

Description: The green turtle is a large sea turtle belonging to the family Cheloniidae. Their common name derives from the green fat underneath their shell. Adult green turtles are known to grow to 1.5 m long. While individuals have been caught that reached weights of up to 315 kilograms, the average weight of mature individuals is around 200 kilograms. The largest Chelonia mydas ever recorded weighed 395 kilograms.

Habitat: The adults are commonly found in shallow lagoons, feeding mostly on various species of seagrass

Ecology: They are mostly herbivorous. Like other sea turtles, green turtles are known to migrate long distances between their feeding grounds and the beaches they hatched from. Many islands worldwide have been called Turtle Islands primarily for the large amounts of green turtles that nest on their beaches each year. Female turtles dredge themselves onto beaches and lay eggs in nests that they dig during the night. After a period of time, hatchlings emerge from the nests and head for the water. Those that survive grow to maturity and live to a maximum of eighty years.

The carapace of the turtle is known to have various color patterns that change over time. Green turtles must breathe air for the oxygen so they come to the surface to breathe yet spend almost all their lives submerged. With a single explosive exhalation and rapid inhalation, sea turtles can quickly replace the air in their lungs. The lungs are adapted to permit a rapid exchange of oxygen and to prevent gasses from being trapped during deep dives. The blood of sea turtles can deliver oxygen efficiently to body tissues even at the pressures encountered during diving.

Turtles can rest or sleep underwater for several hours at a time but submergence time is much shorter while diving for food or to escape predators. Adult green turtles have few enemies and even fewer predators. Only human beings and the the tiger sharks are known predators of adult green turtles.

Interesting facts/Status: Turtle populations are in danger because of several human practices. In some countries, the turtles are still hunted for their flesh and their eggs are collected from nests and eaten as a delicacy. Pollution indirectly harms turtle populations. Many turtles die as a result of being caught in fishermen's nets and drowning.

Green turtles

Green turtle hatchlings

Habitat loss due to human development is a major reason for the loss of green turtle nesting beaches. Of the seven species of marine turtles, six are found in Australian waters and all are considered globally endangered. Climate change is likely to be a major threat to marine turtles given their life history characteristics, such as slow growth rate, and the potential influence of temperature on gender of embryos. Small increases in temperature may strongly bias the sex ratio of hatchlings towards females. Climate-induced changes in food resources will also have an affect.

Green Turtle - Great Barrier Reef