The loggerhead turtle is found around the globe, inhabiting continental shelves, bays, estuaries and lagoons in temperate, subtropical and tropical waters.

Adult loggerhead turtles may attain a shell length of almost 3 m (9 ft.) and weigh up to 454 kg (1,000 lb.) although a length of 1 m (3 ft.) and a weight of about 136 kg (300 lb.) are more usual.

It primarily feeds upon bottom-dwelling invertebrates such as sponges, jellyfish, mussels, clams, oysters and shrimp.

Mating takes place in late March to early June, and the eggs are laid throughout the summer. The female comes ashore at night and digs the nest in the sand with her flippers. She lays round, white, leathery eggs—as many as 150 in a clutch. She then covers them with packed sand.

Any eggs that have not fallen victim to predators hatch after a period of up to 68 days, depending on the temperature. The young loggerheads struggle to the surface and make their way to the sea. The hatchlings are dull brown. They are about 45 mm long (1.8 in.), and weigh on average 20 g (0.7 oz.).

In the Atlantic, these turtles are found from Newfoundland in Canada, to as far south as Argentina; the primary Atlantic nesting sites are along the east coast of Florida (Florida beaches account for one-third of the world's total population). In the eastern Pacific, they are reported as far north as Alaska, and as far south as Chile. The only known breeding area in the North Pacific is in southern Japan.