American Oceans

Biggest Sea Turtles Ranked by Size

There are seven living species of sea turtles, as recognized by scientists worldwide. These species are grouped into six genera.

Leatherback is the biggest living sea turtle

Like other biological organisms, each sea turtle is assigned a scientific name and a common name. The scientific name refers to the genus and species of the turtle, while the common name is more of a description of its physical features.

1.  Leatherback Sea Turtle

The Leatherback is the largest sea turtle existing today, which can reach up to 2000 pounds in weight and 8 feet in size.

Leatherback sea turtle crawling up the beach

These turtles belong to a reptilian family that has been around for more than 100 million years. They derive their name from their shell, which is leather-like in texture.

Their population distribution is the most diverse of all reptile species, as they can be found in the Atlantic, Pacific, and Indian oceans.

Unfortunately, many Leatherbacks die untimely death due to human negligence. Most Leatherbacks or the eggs get caught in large fishing nets or die after colliding with boats.

Due to their rapid decline in population over time, Leatherbacks’ status is listed as Vulnerable according to IUCN.


2.  Green Sea Turtle

One of the largest sea turtles in the world, Green Sea Turtles are the only herbivores amongst their peers. They have a smooth shell that is brown or olive.

Hawaiian Green Sea Turtle cruises in the waters

The average weight of a green sea turtle is anywhere between 600 to 700 pounds, and its size can measure up to five feet.

As mentioned, Green Turtles are herbivores, unlike most other sea turtles. Their diet mainly consists of seagrasses and algae.

However, juvenile green turtles may also feed on invertebrates like crabs, jellyfish, and sponges.

Currently, the Green Turtle population is under continuous threat of habitat loss due to rapid coastal development, hunting, and poaching, which renders them endangered.


3.   Loggerhead Sea Turtle

The Loggerhead Sea turtle is named as such due to its enormous head. It typically measures between 2.5 to 3.5 feet in carapace length, which is bony and rough.

Loggerhead Sea Turtle swimming underwater

On average, an adult loggerhead weighs between 155 and 375 pounds. They are carnivores that primarily feed on shellfish, horseshoe crabs, clams, mussels, etc. They are usually found in the shallow waters of the Atlantic, Pacific, and Indian Oceans.

Rapid human development in coastal areas has threatened the nesting habitat of loggerhead species, causing disorientation and the death of young hatchlings.


4.   Flatback Sea Turtle

Commonly known as the Australian Flatback, the Flatback Sea Turtle is found only in the waters around Australia and Papua New Guinea in the Pacific.

Big adult female Flatback Sea Turtle

Adult flatbacks have an average carapace length of 2.5 to 3 feet and weigh up to 200 pounds.

They are carnivores and feed on sea cucumbers, jellyfish, mollusks, prawns, bryozoans, other invertebrates, and seaweed.

In terms of their habitat, flatback turtles prefer shallow, coastal waters. However, their habitat is under constant threat from coastal developments, ocean pollution, and fishing nets.


5.  Hawksbill Sea Turtle

Hawksbill Sea Turtles are primarily found in the world’s tropical and subtropical oceans. Hawksbills constitute among the largest turtles, with their size being 24 to 45 inches and weighing about 100 to 150 pounds.

Big Hawksbill Sea Turtle swimming in the ocean

Hawksbills are named so because of their pointed beak appearance that resembles a bird beak; moreover, their shells are colored and have a distinctive overlapping pattern. Hence, they are widely traded all around the world, endangering their existence.

Hawksbills are omnivorous; they feed on sea anemones, jellyfish, algae, and sea urchins. There is no appropriate estimate of their population size.

However, according to a rough estimate, 8000+ nesting females have been reported across the globe.


6. Olive Ridley Sea Turtle

Named after their greenish-colored skin and shell, the Olive Ridley Sea Turtle inhabits tropical waters of the Indian, Pacific, and Atlantic oceans.

Olive Ridley Sea Turtle on beach

Their size ranges from 2-2.5 feet, and they weigh approximately 100 pounds. Olive Ridley Turtles have an olive green color and a heart-shaped shell that gives them a unique appearance.

They are omnivorous and feed on jellyfish, snails, crabs, algae, seaweed, and much more. They are abundantly present in many parts of the world, but their numbers are diminishing with time due to their hunt for meat, skin, and accident capture.


7. Kemp’s Ridley Sea Turtle

Kemp’s Ridley is one of the smallest sea turtles found in the Gulf of Mexico, reaching a length of 2 feet and weighing up to 100 pounds.

Kemp's Ridley Sea Turtle released back to ocean

Featuring a triangular-shaped head and a somewhat hooked beak, Kemp’s Ridleys have an off-white colored body and a green-colored shell. Being omnivorous, they feed on crabs, shellfish, seaweed, and sargassum.

Kemp’s Ridley has approximately 7000-9000 nesting females and is the most endangered sea turtle because its eggs are widely harvested for commercial purposes.


8. Archelon (Extinct)

Archelon is an extinct marine turtle that weighed about 4850 pounds measured up to 12 feet in length.

Giant Archelon Turtle 3D generated illustration

Archelon had a leathery shell unlike most sea turtles; moreover, it had large flippers and a sharp pointed beak that could open up shelled animals. Archelon was an omnivore feeding on jellyfish, dead carrions, and plants.

The Archelon became extinct about 66 million years ago due to increased predation of its eggs by other marine and mammalian species. The closest relative of Archelon in the existing world is the Leatherback.

Conclusion

To conclude, it is pertinent to mention that preserving marine life is more crucial than ever. From fisheries bycatch to coastal development and marine pollution, the population of the biggest sea turtles ranked above is rapidly declining with time due to a lack of awareness and measures taken to conserve their habitat and lives.

Without some drastic conservation measures, it may not be long before we might lose some species of these majestic creatures in the times to come.

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