Leatherback Sea Turtle Field Guide — Dermochelys coriacea in Florida
Field guide to the leatherback sea turtle in Florida — the world's largest reptile, its biology, nesting beaches, deep-dive physiology, and conservation status as Florida hosts the only significant leatherback nesting in the continental US.
The leatherback is not built on the same scale as other sea turtles. Where a loggerhead weighs 80–150 kg, a large leatherback weighs 500–700 kg. Where other sea turtles dive to perhaps 100 m, leatherbacks regularly exceed 1,000 m, the deepest confirmed dives of any reptile. Where other sea turtles are limited to tropical and subtropical waters, leatherbacks feed as far north as Norway and the Labrador Sea in summer, generating enough metabolic heat to maintain internal temperatures 18°C above the surrounding water.
ID at a Glance
Leatherbacks are impossible to confuse with any other sea turtle:
- Size: Adult females (the ones you encounter nesting in Florida) typically 1.5–1.8 m carapace length, 300–550 kg. Males are slightly smaller and rarely observed.
- Shell: The defining feature. Not rigid like other sea turtles — a thick, rubbery, leathery skin over a mosaic of small bone fragments and cartilaginous material. Black to dark blue with white or pink spots. Seven prominent longitudinal ridges running the length of the back.
- No scutes: All other sea turtles have clearly defined scute plates. The leatherback has none — a smooth (if bumpy) black leathery surface.
- Head: Large, slightly pink-tinted, with a characteristic deep notch in the upper jaw and flexible jaw structure adapted for jellyfish feeding. No hard beak.
- Front flippers: Enormous — adults have front flippers reaching 2–3 m tip-to-tip. Proportionally the largest flippers of any sea turtle.
- Tracks on beach: Tracks wider than any other sea turtle (over 1 m between flipper prints), with a central body drag and no individual tail drag mark. Track width of 1.5–2 m total. Once you’ve seen leatherback tracks, you will not confuse them with loggerhead tracks.
Taxonomy
Dermochelys coriacea is the sole member of Family Dermochelyidae, and represents a lineage that diverged from all other sea turtles approximately 100 million years ago. It is classified separately from the six remaining sea turtle species (all in Family Cheloniidae). The unique adaptations — leathery shell, endothermy, extreme dive capacity — represent a fundamentally different evolutionary trajectory.
No subspecies are recognized, but genetic analysis identifies distinct population units in the Atlantic, Pacific, and Indo-Pacific. The Florida nesting population is part of the northwestern Atlantic subpopulation, which also nests in Trinidad (the largest nesting concentration) and Suriname.
Range in Florida
Leatherbacks do not reside in Florida waters year-round. Their relationship to Florida is primarily the nesting beach:
Nesting range: The Treasure Coast (Palm Beach through St. Lucie counties) hosts the great majority of Florida nesting. The Archie Carr National Wildlife Refuge (Brevard/Indian River counties) has occasional nesting. Leatherbacks rarely nest south of Palm Beach County or north of Volusia County in Florida.
Peak nesting: March–July, with April–May highest. The Florida nesting population is relatively small — approximately 100–200 nests per year in high years — compared to the 6,000+ nests annually at St. Croix (USVI) or the 15,000+ at Trinidad.
Foraging range: After nesting, female leatherbacks leave Florida and move into the open Atlantic, eventually reaching productive jellyfish feeding grounds in the North Atlantic (including waters off Nova Scotia, Newfoundland, and sometimes Europe). Adult males and non-nesting females are pelagic and widely distributed in the Atlantic.
Incidental presence: Leatherbacks occasionally appear off Florida’s Atlantic coast during spring and fall migrations. They are rarely seen close inshore outside the nesting season.
Behavior
Feeding: Leatherbacks are highly specialized jellyfish predators. Their entire physiology — from the soft jaw adapted to collapse around soft prey, to the papillae (backward-pointing spines) lining the esophagus that prevent jellyfish from escaping, to the tolerance for cold water — is optimized for jellyfish consumption. A large adult may need to consume 200–400 kg of jellyfish per day to meet its metabolic needs, which helps explain the extreme dive depths (jellyfish are abundant in the mesopelagic zone at 200–1,000 m).
Thermoregulation: Leatherbacks are essentially ectotherms with counter-current heat exchange in the flippers and a metabolically-elevated core temperature — a form of “passive endothermy.” Large body mass retains metabolic heat. Core temperatures have been measured at 18°C above surrounding 0°C water in the North Atlantic.
Diving: Confirmed maximum depth: 1,280 m (4,199 ft) — the deepest dive record for any reptile. Dive duration: up to 85 minutes. Routine foraging dives to 300–700 m are common.
Nesting behavior: Females return to nest every 2–3 years. Within a nesting season, they lay 5–9 clutches at roughly 10-day intervals. Clutch size: 50–80 fertile eggs plus approximately 20–30 smaller infertile “spacer eggs.” Egg diameter ~52mm. Incubation: 60–65 days. Females nest at night, typically arriving 1–3 hours after dark. The entire nesting process takes 1–2 hours.
Navigational ability: Leatherbacks imprint on their birth beach and return to the same general area to nest, sometimes with extraordinary precision. Satellite telemetry has shown individuals returning from Nova Scotia to within a few kilometers of their natal beach.
How to Find It
Juno Beach / Loggerhead Marinelife Center, Palm Beach County: The primary research and public engagement site for Florida leatherback nesting. The LMC conducts nightly guided turtle walks April–July. Advance reservation required; walks typically book 3–6 weeks out in peak season. The center also has an active sea turtle rehabilitation program with public exhibits.
Jensen Beach / Martin County: Martin County’s beaches host significant leatherback nesting. The Sea Turtle Oversight Protection (STOP) program offers permitted nesting watches. Bathtub Reef Beach and Hobe Sound NWR are known sites.
Hobe Sound National Wildlife Refuge, Martin County: Protected beach habitat with documented leatherback nesting. FWS manages the beach for sea turtle protection; organized watches are offered seasonally.
Self-guided observation rules: If you encounter a nesting turtle on your own, maintain at least 30 m distance until she is fully committed to nesting (front flippers excavating — at this point she typically will not abort the nesting attempt). Do not use any white light. Stay behind the turtle, never between turtle and ocean. Do not touch.
Timing: Late March through June for nesting. Peak on Treasure Coast beaches is April–May. Arrive at the beach after 10pm on weeknights for lowest crowd interference. Full-moon nights are sometimes harder — brighter beaches deter some turtles and attract more observers.
Conservation
IUCN Status: Vulnerable (VU) globally. Some subpopulations (Pacific) are Critically Endangered. The northwest Atlantic population (including Florida) is considered the healthiest and most stable.
ESA Status: Endangered (US). Listed since 1970.
Florida population trends: The Treasure Coast population showed significant decline from the 1980s through approximately 2000, followed by recovery. Current trend: stable to slightly increasing in Florida, consistent with northwest Atlantic recovery trend.
Primary threats:
- Longline bycatch — the most significant threat to adult leatherbacks at sea. Pacific populations were devastated by Pacific longline fisheries in the 1980s–2000s.
- Plastic ingestion — floating plastic bags resemble jellyfish. Leatherbacks are highly vulnerable to plastic debris in the world’s oceans.
- Beach armoring and artificial lighting — coastal development reduces nesting beach availability and artificial lights disorient hatchlings
- Egg harvest — legally prohibited in Florida; still a pressure in parts of the Caribbean range
- Climate change — rising sand temperatures affect incubation and sex ratios; sea level rise threatens low-elevation nesting beaches
What’s being done:
- Archie Carr NWR and Sea Turtle Overlay District protect critical nesting beach in Florida
- Loggerhead Marinelife Center nest monitoring, hatchling release programs
- Longline turtle excluder devices and fishing closures in critical areas
- International nesting beach protection (Trinidad, Suriname)
- Beach lighting ordinances in coastal counties
Florida’s Treasure Coast nesting population is one reason the northwest Atlantic leatherback is considered a conservation success relative to the critically endangered Pacific population.
