Identification guide 02 species

How to Tell Sea Turtles Apart

Two sea turtles nest on Japan's beaches and greet visitors at its aquariums. Tell the green turtle and the loggerhead apart by head size, the scales between the eyes, and carapace colour — the names refer to body colour, not the shell.

Identification steps

3 steps

  1. 1

    Look at the size of the head

    A head that is large for the body, with sturdy jaws, means a Loggerhead Sea Turtle — it has a powerful head for crushing shellfish and crustaceans. A smaller, rounded head means a Green Sea Turtle.

  2. 2

    Count the scales between the eyes

    The sure method is the number of prefrontal scales (the scales between the eyes). One pair (2 scales) means a Green Sea Turtle; two pairs (4 scales) means a Loggerhead.

  3. 3

    Finish with the shell color

    A reddish-brown, broad shell means a Loggerhead; an olive-to-brown, smooth shell means a Green Sea Turtle. The "ao" (green) in the Japanese name refers to its greenish body fat — the shell itself is not green.

Representative species of Japanese waters (told apart by the head and scales)

2 species

Green Sea Turtle
Photo: Charles J. Sharp / CC BY-SA 4.0 / Source / cropped

Identification specimen green-sea-turtle

Green Sea Turtleアオウミガメ

Chelonia mydasEN— Endangered

Size
Carapace length about 80–100 cm
Key features
A smallish head, with one pair of prefrontal scales between the eyes. Adults are herbivores feeding mainly on seagrass and seaweed, and the shell is smooth. The name comes from its greenish body fat.
Habitat
Tropical and subtropical seas worldwide

Where to see this species

Port of Nagoya Public AquariumKamogawa Sea WorldSusami Chouritsu Ebitokanino Suizokukan11 more
Green Sea Turtle species profile
Loggerhead Sea Turtle
Photo: ukanda / CC BY 2.0 / Source / cropped

Identification specimen loggerhead-sea-turtle

Loggerhead Sea Turtleアカウミガメ

Caretta carettaVU— Vulnerable

Size
Carapace length about 70–100 cm
Key features
A head that is large for the body, with powerful jaws. Two pairs of prefrontal scales. A carnivore that crushes shellfish and crustaceans; the shell is reddish brown. Japan's beaches are among the world's major nesting sites.
Habitat
Temperate to tropical Pacific, Indian, and Atlantic Oceans

Where to see this species

Port of Nagoya Public AquariumKamogawa Sea WorldMurotohaikou Suizokukan7 more
Loggerhead Sea Turtle species profile

Compare similar species

1 pairs

Green Sea Turtle vs Loggerhead Sea Turtle

Reliably told apart by the size of the head and the scales between the eyes.

Green Sea Turtle Green Sea Turtle Loggerhead Sea Turtle Loggerhead Sea Turtle
FeatureGreen Sea TurtleLoggerhead Sea Turtle
Head size Smallish and rounded Large for the body, with powerful jaws
Scales between the eyes (prefrontal scales) One pair (2 scales) Two pairs (4 scales)
Shell color Olive to brown, smooth Reddish brown, broad
Main diet Seagrass and seaweed as adults (herbivore) Shellfish and crustaceans (carnivore)

Books & gear

Sources

Guide sources: ja.wikipedia.org en.wikipedia.org / Photos: see the Commons credit links beside each image.