The leatherback sea turtle (Dermochelys coriacea) is the world’s largest turtle, weighing between 250 and 700 kilograms. Instead of having a bony shell like other sea turtle, the leatherback has a leathery carapace made up of skin and oily tissue. They are mainly grey/black in colour with frequent white spots in places. Their dark dorsal surface contrasts their lighter underside – demonstrating countershading.
Countershading is an effective camouflage technique incorporated by many species so when light hits them from above, they are harder to detect by predators. This is especially important within newborn leatherbacks as they are vulnerable to a plethora of predators such as seabirds, crabs, monitor lizards, dogs, coyotes and mongooses (depending on their nesting site) and that’s just while they’re on the shore. Once the survivors reach the ocean, they face even more predation from cephalopods, sharks, other large fish and more seabirds.
The leatherback turtle has a worldwide distribution, which includes subarctic waters, and one of the largest migratory journeys. The leatherback’s diet consists almost entirely of jellyfish; Pacific leatherbacks migrate nearly 10,000 kilometres across the Pacific Ocean from Indonesia to California just to feed on the abundant jellyfish found there. Sadly, Californians use billions of plastic bags every year and many of these end up in the ocean where leatherbacks mistake these floating plastics for jellyfish. This is one of the causes of the leatherback’s ‘vulnerable’ status by the IUCN, but many subpopulations are listed as ‘critically endangered’. By consuming even small quantities of plastic debris, the leatherback’s digestive tract can become clogged, often leading to nutrient deficiencies or death.
Along with plastic rubbish, the leatherback sea turtle is also threatened by people who harvest their eggs, particularly in Southeast Asia where sea turtle eggs are considered a delicacy. This has led to a complete decline in leatherback sea turtles rendering them locally extinct in countries such as Malaysia. Moreover, leatherbacks play a vital role in marine ecosystems by keeping jellyfish populations low so their decline damages the entire food chain and has had knock-on effects to other species (due to species interdependence).
The leatherback turtle is yet another species which is rapidly declining at the hands of Homo sapiens. As the only extant species in the family Dermochelyidae, this reptilian is a truly prehistoric and unique animal which faces extinction, but we can help. By reducing the demand for turtle eggs, minimising our plastic pollution and establishing conservation schemes, we can hopefully help to protect thousands of marine and aquatic species which are suffering the same torture as the leatherback. Even by just refusing a plastic bag in a supermarket, maybe one animal, somewhere in the world, can live a while longer…