The leatherback sea turtle is the largest sea turtle species, lacking the hard, bony shell of its relatives. Its carapace is covered by thick, oily, and flexible skin, giving the animal a distinctive, leathery appearance. This oceanic giant undertakes vast migrations, prompting questions about the source of energy required for such a massive reptile. A fundamental question for understanding its biology is whether this deep-diving traveler is a carnivore.
The Leatherback’s Strict Dietary Classification
The answer is yes; the leatherback sea turtle is classified as a carnivore, meaning it derives its energy and nutrients almost entirely from animal tissue. Unlike other sea turtle species, the leatherback is a highly specialized, obligate carnivore. Its diet centers on hunting and consuming soft-bodied organisms found in the water column. This specialized feeding habit has earned it the descriptive nickname of a “gelatinivore” among researchers.
The Exclusive Diet of Gelatinous Prey
This carnivore’s diet is almost exclusively composed of gelatinous plankton, primarily various species of jellyfish and salps. Because these prey items are roughly 95% water, they have an extremely low caloric density. To compensate for this nutritionally poor food source, the leatherback must engage in hyperphagia, consuming massive quantities of food. Researchers estimate that an adult leatherback must consume wet mass equivalent to 50% to 73% of its own body weight daily to meet its metabolic needs.
This immense consumption rate means a large turtle can ingest hundreds of jellyfish daily during its foraging season. Unfortunately, this dietary preference creates a significant vulnerability for the species. Floating plastic bags closely resemble their primary jellyfish prey, leading the turtles to mistake them for food. Ingesting this plastic debris can severely impact the leatherback’s digestive system, linking its specialized diet to a major conservation threat.
Anatomical Adaptations for Specialized Predation
The leatherback possesses adaptations that enable it to efficiently capture and process its diet. The most striking adaptation is found within its esophagus, which is lined with hundreds of specialized, backward-pointing spines called papillae. These keratinized structures extend down the throat and act like an internal conveyor belt, preventing the jellyfish from slipping back out once captured. They also help shred the soft-bodied prey as it moves toward the stomach for digestion.
The turtle’s jaws are also modified for its diet, featuring delicate, scissor-like edges suited for biting into the soft bells of jellyfish. Beyond its feeding anatomy, the leatherback has an adaptation that allows it to hunt across vast, cold ocean regions. It exhibits gigantothermy, where its large body size, thick fat layer, and specialized circulatory systems allow it to retain metabolically generated heat. This capability allows the leatherback to maintain a core body temperature up to 8°C warmer than the surrounding water, making it the only sea turtle able to hunt for jellyfish in the frigid waters of high latitudes.