Leatherback sea turtles are marine reptiles known for their immense size and unique physical characteristics. They are the largest living turtle species, often reaching lengths of up to 8 feet and weighing over 2,000 pounds. Unlike other sea turtles, they possess a flexible, leathery shell, which gives them their distinctive name. This ancient lineage has roamed the oceans for approximately 100 million years.
The Exclusive Jellyfish Diet
Leatherback sea turtles are highly specialized feeders, primarily consuming jellyfish and other gelatinous zooplankton. Their diet includes species like lion’s mane and moon jellyfish, which they encounter across their vast migratory paths. Despite jellyfish being largely composed of water and having low nutritional content, leatherbacks compensate by consuming immense quantities.
An adult leatherback can consume up to 73% of its own body weight in jellyfish per day. They consume hundreds of kilograms daily, with estimates ranging from 330 kg to 840 kg of wet mass, or 261 to 664 jellyfish. This high volume of consumption allows them to meet their substantial energy requirements, supporting their growth and extensive migrations.
Specialized Feeding Adaptations
Leatherback sea turtles possess anatomical features enabling them to efficiently capture and process slippery, gelatinous prey. Their mouth structure includes sharp-edged jaws with pointed cusps, which help to pierce and hold jellyfish. Unlike many other turtle species, leatherbacks do not have crushing plates in their mouths, as their diet consists of soft-bodied organisms.
Thousands of backward-pointing spines, called papillae, line their esophagus and throat. These papillae function like a one-way filter, ensuring that once a jellyfish is ingested, it cannot escape and is guided towards the stomach. This lining also helps to expel excess seawater, prevent prey from escaping, and may offer protection from jellyfish stings.
Threats from Mimicked Prey
Their specialized diet makes leatherbacks vulnerable to marine plastic pollution. Plastic bags and balloons floating in the ocean resemble jellyfish, leading to accidental ingestion. Autopsy records reveal plastic in leatherbacks’ gastrointestinal tracts, highlighting the issue’s prevalence.
Ingesting plastic can cause blockages in their digestive system, leading to reduced digestive efficiency, malnutrition, and death. The backward-pointing papillae, beneficial for consuming jellyfish, make it nearly impossible to regurgitate ingested plastic. This environmental hazard threatens leatherback populations globally.