The Leatherback Sea Turtle, Dermochelys coriacea, is the largest and most unique of all sea turtle species, recognized by its soft, leathery carapace instead of a hard bony shell. Its massive size, often exceeding 1,000 pounds, requires a steady food supply to fuel its extensive migrations across the world’s oceans. While the question of whether this giant marine reptile is an omnivore is common, the definitive answer is that the leatherback sea turtle is not an omnivore. It is a highly specialized predator whose life history revolves around a single, specific food source.
The Definitive Answer: Specialized Carnivore
Leatherback sea turtles are classified as carnivores, exhibiting an extreme specialization unlike most other large vertebrates. Their feeding habits are so focused that some scientists refer to them as “gelatinivores,” a term that perfectly describes their dietary niche. They subsist almost entirely on soft-bodied, gelatinous zooplankton, which is animal matter. This specialized preference distinguishes them from other sea turtles, such as the Green Sea Turtle, which transitions to a predominantly herbivorous diet as an adult. Its entire physiology, from its deep-diving ability to its unique digestive tract, is adapted for catching and processing this slippery, low-density prey.
Primary Food Sources and Massive Consumption
The primary components of the leatherback’s diet are jellyfish and salps, which are abundant in the deep-sea foraging zones. Species such as the Lion’s Mane jellyfish (Cyanea capillata) are common prey, particularly in the high-latitude feeding grounds the turtles migrate to. This focus on gelatinous prey is efficient because these animals often occur in dense, predictable patches, making them an easy target for a large predator.
This diet presents a significant challenge due to its low nutritional value, as jellyfish are composed of up to 96% water. The low energy density requires the leatherback to engage in hyperphagia, or extreme overeating. To compensate for meager calories, an adult must consume an average of 73% of its own body mass daily, translating to hundreds of kilograms of jellyfish. This volume is necessary to meet the high metabolic demands of maintaining its massive size and undertaking long migrations. Unfortunately, this foraging behavior, which focuses on clear, floating, soft-bodied items, means floating plastic bags are frequently mistaken for jellyfish, and accidental ingestion is a significant cause of mortality.
Unique Adaptations for Gelatinous Prey
The leatherback possesses a suite of remarkable physical adaptations that allow it to successfully hunt and process its unique, slippery food source. Unlike other sea turtles, it lacks the crushing jaw plates for hard-shelled prey. Instead, it has sharp-edged jaws with two pointed cusps on the upper jaw for grasping soft-bodied organisms. This specialized beak allows the turtle to efficiently capture and slice through the bell of a large jellyfish.
The most striking adaptation is found lining its entire esophagus and throat: hundreds of backward-pointing, spine-like structures called papillae. These papillae, which are made of keratin, function as an internal conveyor belt. Their pointed orientation ensures that once a slippery jellyfish is swallowed, it cannot slide back out of the mouth.
This internal lining also plays a crucial role in managing the large amount of seawater ingested with the low-density prey. The papillae help to squeeze and expel excess water from the food mass before it reaches the stomach, effectively acting as a reverse filter. This mechanism allows the leatherback to maximize its energy intake from the sparse gelatinous material while reducing the intake of highly saline water.