Eretmochelys imbricata

Lore & Background

Unlike every other sea turtle, the leatherback's shell is a thick, flexible dermal layer studded with seven longitudinal keels rather than bony scutes. This architecture, combined with a layer of insulating fat up to 5 cm thick, allows it to maintain a core body temperature several degrees above ambient water, a trait unique among reptiles of its size. This physiological advantage underpins its ecological niche: foraging at depths where no other sea turtle ventures, snatching moon jellies and siphonophores from the twilight and midnight zones.

Its migratory range is staggering. Individuals have been tracked crossing entire ocean basins, travelling more than 6,000 km between tropical nesting beaches in the Atlantic or Indian Ocean and temperate feeding grounds in the North Atlantic or North Pacific. The leatherback is the only sea turtle documented to cross the equator, linking hemispheres in a single foraging circuit. Females return to the same beach where they hatched—a fidelity that makes the loss of even one nesting site a generational blow.

In West African and Southeast Asian cultures the leatherback has long been a target of egg harvesters and meat traders, and its thick, oily carapace was once prized for leather goods. The CITES Appendix I listing, in force since the Convention's entry into force in 1975, was a direct response to this trade. Yet the species' recovery has been stymied not by legal markets but by incidental mortality in longline, trawl, and gillnet fisheries, and by the warming of sand temperatures that skews hatchling sex ratios heavily toward females.

Reader's Guide

Bycatch in industrial fisheries. The leatherback's deep-diving foraging behaviour and large body size make it especially vulnerable to entanglement in longline hooks, trawl nets, and gillnets. It is the only sea turtle that regularly forages below 600 m, placing it in the operating depth of deep-set longlines and bottom trawls. IUCN (2019) lists bycatch as the primary driver of its Critically Endangered status. Mitigations include turtle-excluder devices (TEDs) in trawl fisheries, circle hooks, and night-setting of longlines, but compliance remains patchy, particularly in high-seas and small-scale operations.

Climate change and temperature-dependent sex determination. Leatherback hatchling sex is determined by incubation temperature; prolonged warming of nesting sand in West Africa and the Caribbean has produced sex ratios exceeding 95 % female in some monitored clutches. This skews the breeding population and threatens long-term genetic diversity. No direct intervention exists for sand temperature; management focuses on preserving shade, vegetation, and dune structure at nesting sites.

Nesting-beach degradation and egg harvest. Coastal development, tourism infrastructure, and residual illegal egg collection reduce viable nesting substrate. CITES Appendix I prohibits international commercial trade in leatherback products, and most range states have domestic protections. However, enforcement in remote West African and Southeast Asian beach communities remains inconsistent, and poaching of eggs persists in several countries despite legal bans.

Plastic and marine debris ingestion. Leatherbacks, feeding indiscriminately on gelatinous prey, readily ingest plastic bags and film that resemble jellyfish. Documented cases of intestinal blockage and mortality have been reported. No regulatory framework specifically targets this threat; it is addressed indirectly through broader marine-debris reduction programmes under the London Convention and regional action plans.

Did You Know?

• The leatherback is the only sea turtle that forages in the bathypelagic zone, with verified dive records exceeding 1,000 m—deeper than any other extant sea turtle.
• It is the only sea turtle known to migrate across the equator, linking feeding and nesting grounds in both hemispheres in a single circuit.
• Its core body temperature can exceed ambient water by up to 5 °C, a degree of endothermy unmatched in other reptiles of comparable size.
• It is the sole surviving member of the family Dermochelyidae; all other lineages within the family are extinct.