A Guide to Identifying the Seven Sea Turtle Species
There are only seven recognized species of sea turtles worldwide. While they share a global range, distinguishing between them requires attention to detail. Identification relies on specific physical markers rather than general appearance.
To identify a sea turtle, you generally look at three key areas:
- The Head: Specifically the “Prefrontal Scales” between the eyes.
- The Carapace (Shell): The number and pattern of “scutes” (plates) on the back.
- The Plastron (Belly): In some species, pores on the belly scales are the giveaway.
There are seven distinct species of sea turtles navigating our oceans. Use the chart below to identify them by their shell patterns and scales, then explore the detailed breakdowns further down the page.
Sea Turtle Identification Chart
Leatherback
Leathery shell. No scutes.
Hard Carapace
Hard shell with scutes.
4 Costal Scutes
First scute doesn’t touch neck.
Hawksbill
2 Pairs Scales.
1 Pair Scales
Between eyes.
Flatback
Upturned shell.
Green
Smooth shell.
5 or more Costal Scutes
First scute touches neck.
Circular Shell
Wide & Round.
Kemp’s Ridley
5 Scutes.
Olive Ridley
6+ Scutes.
Loggerhead
Elongated shell.
Quick ID Tip: Check the Map!
Location is the most efficient way to narrow the possibilities. Flatback turtles are endemic to the Australian continental shelf; sightings outside this region are statistically negligible. Similarly, Kemp’s Ridleys are concentrated in the Gulf of Mexico and the North Atlantic. Always apply geographical range as your first filter before counting scales.
Sea Turtle Shell Anatomy Reference
Species Profiles
Loggerhead Sea Turtle
250–300 lbs
(Atlantic, Pacific, Indian)
(Decreasing)
Identification Profile
Distinguishing Features: Named for its massive, blocky head. The carapace is reddish-brown and elongated (tapering slightly at the rear).
Diet: Carnivores. Their massive jaws are designed for crushing hard-shelled prey like conch, crabs, and clams.
Green Sea Turtle
300–400 lbs
(Global)
(Decreasing)
Identification Profile
Distinguishing Features: Named for the color of its fat (not its shell). It has a smooth, oval carapace and a rounded head with only 1 pair of prefrontal scales between the eyes.
Diet: Herbivores (Adults). They are the only sea turtle species that feeds strictly on seagrass and algae, maintaining the health of seagrass beds through constant grazing.
Hawksbill Sea Turtle
100–150 lbs
(Atlantic, Pacific, Indian)
(Decreasing)
Identification Profile
Distinguishing Features: Named for its narrow, pointed beak. The shell has overlapping scutes (like roof shingles) and a serrated edge.
Diet: Spongivores. They feed almost exclusively on sponges found in coral reefs, helping to keep the reef healthy by preventing sponges from overgrowing corals.
Leatherback Sea Turtle
550–1,500 lbs
(Tropical to Sub-Polar)
(Decreasing)
Identification Profile
Distinguishing Features: The only sea turtle without a hard shell. Its carapace is leathery, inky blue-black, and flexible, with 7 distinct ridges running lengthwise.
Diet: Gelatinous feeders. They feed almost exclusively on jellyfish and salps, which helps control jellyfish populations in the oceans.
Flatback Sea Turtle
180–200 lbs
(Continental Shelf)
(Data Deficient)
Identification Profile
Distinguishing Features: Has a very flat carapace with edges that curl upward (like the brim of a hat). It has thinner skin than other species, which can feel easily bruised.
Diet: Omnivores. They forage in shallow, murky waters for sea cucumbers, soft corals, jellyfish, and prawns.
Kemp’s Ridley Sea Turtle
75–100 lbs
& US Atlantic Coast
(The Rarest Species)
Identification Profile
Distinguishing Features: The smallest sea turtle. It has a very circular, light gray-green shell. It is the only species that nests primarily during the day.
Diet: Carnivores. They prefer swimming crabs, which is why they stay in shallower, muddy, or sandy coastal waters.
Olive Ridley Sea Turtle
80–110 lbs
(Pacific, Indian, South Atlantic)
Identification Profile
Distinguishing Features: Famous for Arribadas (synchronized mass nesting). It has 6 to 9 costal scutes, which is unique (most other hard-shelled turtles have 4 or 5), and the number is often asymmetrical.
Diet: Omnivores. They eat crabs, shrimp, lobsters, urchins, jellyfish, algae, and fish.
The Cycle: A Game of Numbers
Sea turtle reproduction is defined by Natal Homing. Females possess the ability to imprint on the magnetic signature of their birth beach, returning decades later to lay their own clutches.
The process is high-risk. A female may lay hundreds of eggs in a season, but the survival rate is brutal. Biologists estimate that only 1 in 1,000 hatchlings survives to sexual maturity.
Hatchlings emerging in Laamu Atoll, Maldives
Temperature-Dependent Sex Determination (TSD): The sand temperature determines the sex of the hatchlings. Warmer sands produce females, while cooler sands produce males. This mechanism makes sea turtle populations particularly vulnerable to rising global temperatures.
Quick Comparison Table
| Species | Costal Scutes | Prefrontal Scales | Inframargin Scutes | Key Feature |
|---|---|---|---|---|
| Leatherback | None | None | None | Leathery shell with ridges |
| Hawksbill | 4 (no nuchal contact) | 2 pairs | 4 (no pores) | Overlapping scutes, hawk beak |
| Flatback | 4 | 1 pair | 4 (no pores) | Flat shell, Australia only |
| Green | 4 | 1 pair | 4 (no pores) | Serrated lower jaw, herbivore |
| Kemp's Ridley | 5 (circular) | More than 1 pair | 4 (with pores) | Smallest, nearly circular shell |
| Olive Ridley | 6+ (variable) | More than 1 pair | 4 (with pores) | 6+ vertebral scutes, mass nesting |
| Loggerhead | 5 | More than 1 pair | 3 (no pores) | Massive head, reddish-brown |