The leatherback sea turtle (Dermochelys coriacea) is the largest turtle species on Earth. Unlike other sea turtles, it lacks a bony shell, instead possessing a smooth, leathery carapace supported by a mosaic of small bones beneath the skin. This unique structure, combined with a large body size (up to 2,000 pounds and seven feet in length), helps it undertake vast trans-oceanic migrations. It is also the deepest-diving reptile, regularly reaching depths of 4,000 feet to forage across the water column. Despite these impressive physical adaptations, the species is highly vulnerable to predation throughout much of its life cycle.
Predation at the Nesting Stage
The period of highest vulnerability occurs on the nesting beach, where eggs and emerging hatchlings face an intense gauntlet of predators. Female turtles typically deposit clutches of 60 to 120 eggs, sometimes up to five times per season, but the survival rate to adulthood is extremely low. Coastal mammals and invertebrates are the primary threats to the subterranean nests, often relying on scent to locate the buried eggs.
Terrestrial predators frequently dig up nests to consume the soft-shelled eggs. These include raccoons, dogs, pigs, coyotes, and coatis. Monitor lizards are also significant nest raiders in certain regions, while nesting females can be attacked by jaguars or saltwater crocodiles. Once hatchlings emerge, they face a desperate dash across the beach toward the ocean, a journey fraught with danger.
Ghost crabs are efficient predators on the beach, lurking in the sand and preying on the small hatchlings as they crawl. Above them, avian predators, including gulls, frigatebirds, and various raptors, swoop down to snatch the young turtles. As they enter the surf zone, the danger continues, with waiting carnivorous fish and small requiem sharks consuming large numbers. The volume of predation at this stage means most individuals are lost before they leave coastal waters, making it the most significant bottleneck in the leatherback life cycle.
Threats to Young Leatherbacks in the Ocean
For the few hatchlings that successfully navigate the near-shore waters, the open ocean presents a considerable array of threats. During the juvenile and sub-adult phases, the turtles are too small to benefit from the invulnerability of the adults, but they are rapidly growing. This makes them a viable meal for larger, pelagic hunters that patrol the deep sea.
Young leatherbacks are preyed upon by various large predatory fish and cephalopods. However, the most significant threat during this transitional period comes from large, powerful sharks, such as the Tiger Shark and Bull Shark. These predators are capable of overwhelming the growing turtle before it reaches its maximum protective size.
The turtle’s defense shifts from camouflage to using agility and diving capabilities to evade attack. While the leathery carapace provides some protection, it is not the hard, bony shell of other sea turtles, meaning a sustained attack can be effective. The period between roughly one and five years of age represents a race against time to outsize its primary oceanic predators.
The Apex Predators of Mature Leatherbacks
Once a leatherback reaches its full adult size (up to 2,000 pounds and seven feet long), it is virtually immune to natural predation. This immense bulk, combined with its deep-diving ability, makes it a difficult and uneconomical target for most marine carnivores. Only the ocean’s true apex predators are capable of occasionally preying on a healthy, full-grown adult.
Orcas, or Killer Whales, are among the few animals that can successfully attack an adult leatherback. These highly intelligent marine mammals often hunt in coordinated groups, targeting a turtle’s vulnerable flippers to immobilize it. Although the leatherback’s soft carapace is thicker and more flexible than a hard shell, it offers little defense against the crushing bite force of an Orca pod.
Great White Sharks and large Tiger Sharks are also opportunistic predators of adult leatherbacks. While a Tiger Shark may sometimes take a bite out of a flipper, a full-scale predation event on a massive, healthy adult is rare. Scientists agree that the adult leatherback’s sheer size and protective leathery skin provide an effective shield against nearly all natural threats.