How Big Is a Leatherback Sea Turtle? Size and Records

Typical adult size

Sea turtle size is usually given as curved carapace length (CCL), measured with a flexible tape along the curve of the shell from the neck to the tip. For adult leatherback sea turtles, CCL is commonly between about 1.3 and 1.8 m (4.3 and 6 ft). Add the head and the tail, and the whole animal is roughly 1.8 to 2.2 m (6 to 7 ft) long.

Weight varies a lot with population and condition. Nesting females in the Caribbean have averaged about 380 kg (840 lb), and those in French Guiana about 340 kg (750 lb). Pacific leatherbacks tend to be somewhat smaller than Atlantic ones. The front flippers are very long, and in large adults they can span about 2.7 m (9 ft) from tip to tip, wider than the turtle is long.

The Harlech turtle and other records

The most famous leatherback of all washed up dead on the beach at Harlech in northwest Wales in September 1988. This male, drowned after becoming tangled in fishing gear, was reported to weigh 916 kg (2,019 lb) and to measure about 2.9 m (9.5 ft) in total length. For decades it was quoted as the largest turtle ever recorded, and its preserved body went on display at the National Museum in Cardiff.

Those numbers are now treated with caution. Later examination of the preserved specimen suggested that its shell is considerably shorter than first reported, which also casts doubt on the original weight. Reliable weights of about 650 kg (1,430 lb) have been recorded for exceptionally large leatherbacks, and some sources mention animals approaching 900 kg (2,000 lb), but well-documented individuals over about 700 kg (1,540 lb) are rare.

How leatherbacks grow so large

A leatherback hatchling weighs only about 45 g (1.6 oz), so an adult is several thousand times heavier. The young grow fast for reptiles, fueled by a diet of jellyfish that the adults may eat in amounts equal to more than half their body weight in a day. Estimates of how long it takes to reach adult size vary widely, from under 10 years to around 30 years, depending on the study method.

Large size is useful for an animal that feeds in cold seas. A big body loses heat slowly, and the leatherback adds a thick layer of oily fat and special blood vessels in its flippers that hold warmth in. This lets it hunt jellyfish in water far colder than other sea turtles can tolerate, as covered in how deep can leatherbacks dive.

Leatherbacks compared with other sea turtles

There are seven living species of sea turtles, and the leatherback is far larger than any of them. The next biggest are the green sea turtle and the loggerhead, which usually weigh up to about 200 kg (440 lb). The smallest, Kemp’s ridley, weighs only around 35 to 50 kg (75 to 110 lb).

The leatherback also outweighs every land tortoise. Exceptional Galápagos giant tortoises can pass 400 kg (880 lb), but most adults weigh far less, and even the biggest fall short of a large adult leatherback.

Archelon and other giant sea turtles of the past

Leatherbacks are giants today, but they were not the largest turtles ever. Archelon ischyros, which swam in the shallow sea that covered central North America about 70 to 80 million years ago, reached about 4 m (13 ft) or more from head to tail and is estimated to have weighed more than 2 tonnes. Like the leatherback, it lacked a solid bony shell, though scientists debate how closely the two are related.

Even so, the leatherback is among the heaviest living reptiles. Only the largest crocodiles, such as the saltwater crocodile, clearly outweigh it. For other record-sized creatures, see the largest animals in the world.