Name: Leatherback Sea Turtles
Average Weight: 660 - 1,100 pounds
Average Size: 4 - 6 feet
Lifespan in the Wild: 45 years
IUCN Status: Vulnerable
Population: It is estimated that there are between 34,000 and 36,000 nesting females. It is worth noting that these estimates are based on nesting beach monitoring reports and publications. IUCN acknowledges that their populations are decreasing.
General Information: Leatherback sea turtles are the largest of all the species, they are able to grow up to 7 feet long and weighing over 2,000 pounds! They are named leatherbacks because unlike other sea turtles they have a softer shell that is leather-like.
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These sea turtles feed almost exclusively on jellyfish. This is largely due to the fact that they have delicate jaws and require a diet of soft bodied prey. Researchers have in the past made a link between the decline in leatherback populations and increased jellyfish numbers.
Nesting Behaviours & Reproduction:
Female leatherback turtles will return to the same region to nest, though they may change the beaches that they choose to nest on, when they reach sexual maturity between the ages of 15 - 25 years old. They typically nest every 2 to 3 years, after mating out at sea they crawl up the beaches during the night and will lay 4 to 7 nests roughly every 10 days. On average each clutch will hold 80 fertilized eggs of a slightly larger size and then a further 30 smaller, unfertilized.
After incubating for about 65 days hatchlings will emerge from the nest with the temperature of the nest determining the sex of the hatchlings. They make their way to the ocean, it is estimated that 10% of the hatchlings will be eatten by predators such as crabs, reptiles and birds, only 25% will survive their first few days in the ocean and just 6% will survive their first year.
Habitat & Range:
They have a massive range having been found as far north as Alaska all the way down to New Zealand and South America. Found in both tropical and temperate waters around the world and they undertake one of the greatest migration between their feeding grounds and their breeding grounds, averaging 3,700 miles each way.
This species of sea turtle is the only one to live in colder waters because unlike their fellow ocean dwelling turtles they are more adapted to transversing cold water. Their large size and ability to alter their swimming activity and blood flow allows them to both generate and retain body heat.
Threats To The Species:
In the Atlantic the number of leatherback sea turtles appears to be stable, even increasing, where as in the Pacific their numbers are dramatically decreasing with some Pacific populations having disappeared entirely.
Part of the decline to the Pacific population is thought to be due to egg harvesting for use as aphrodisiacs.
According to the WWF, hundreds of thousands of sea turtles are accidentally caught in shrimp trawl nets, on longline hooks and in fishing gilnets each year and leatherback sea turtles are no exception. Sea turtles need to surface for air, and if they get caught up in fishing gear meant for other sea life they will tragically drown.
A lack of control on coastal development sees their nesting beaches disturbed and destroyed, frequent vehicle traffic across the beach along with more and more human activities leads to the destruction of nests. This coupled with sea levels rising leaves them with drastically reduced nesting locations.
As the leatherback turtle feasts largely on soft vertebrae prey, they often fall victim to plastic pollution, mistaking items like plastic bags for jellyfish floating on the ocean. A large build up of plastic in their digestive system will ultimately result in death.