Sea turtles – wanderer of the oceans
Sea turtles can weigh up to 2000 pounds and are believed to reach up to 100 years of age. They are elegant and tenacious swimmers. On land, however, they are very ponderous and every move takes a lot of energy. Only the females have to come ashore on a sandy beach from time to time to build a nest and lay their eggs.
Turtles have an incredible sense of direction which the scientists are still unable to fully explain although research suggests that the turtles use the earth magnetic field. At the age of 10-20 years the female turtles hit land for the first time when they return to exactly that beach, where they were born themselves, in order to lay their eggs there. On their journey back to their place of birth they sometimes cover enormous distances and even cross oceans.
A female can be fertilized by several males. Thereafter the female comes ashore usually 3 to 5 times, at intervals of 10 to 15 days, to build a nest and lay about 100 eggs each time. In order to avoid the heat and the dangers of the day turtles usually lay their eggs during the night. Having dragged themselves across the beach they search for a suitable spot and start shoveling a hollow in the sand using their front flippers. Thereafter they dig a hole of up to 27 inches deep by using their rear flippers. This is where the eggs are laid into. Finally the whole nest has to be covered by sand again. After hours of extremely hard work the turtles being close to exhaustion have to crawl back to the sea.
After about 60 days the hatchlings hatch out of their eggs deep in the nest. They wriggle in the sand, which brings them all toward the surface together, and then they all run toward the sea. Only just 2.4 inches long they now encounter the most dangerous period of their life. Many of them are eaten by crabs, birds, octopus and big fish and some die from starvation or illness. Only about one or two out of 1000 hatchlings survive and grow into an adult turtle. However, once fully grown only two enemies are left to the turtles: sharks and Mankind.
Currently we kno seven species of sea turtles:
- Leatherback sea turtle (Dermochelys choriacea)
- Green sea turtle (Chelonia mydas)
- Hawksbill sea turtle (Eretmochelys imbricata)
- Loggerhead sea turtle (Caretta caretta)
- Olive Ridley sea turtle (Lepidochelys olivacea)
- Kemp’s ridley (Lepidochelys kempii)
- Flatback sea turtle (Natator depressus)
Nearly all species are redlisted by the IUCN (International Union for Conservation of Nature and Natural Resources) as “vulnerable”, “endangered” or “critically endangered”; only for the flatback, which lives only in Australian waters and in the south of New Guinea, the status is unclear since reliable data are currently deficient.