Loggerhead turtles (Caretta caretta) are named after their exceptionally large heads. They normally carry many encrusting organisms, such as barnacles, on their head and carapace. Adult loggerhead turtles measure between 75 and 100 cm in length and typically weigh up to 160 kg. The largest recorded loggerhead weighed 545 kg and measured 213 cm in length. Their heart-shaped carapace is orange to reddish-brown with a yellowish-brown plastron. They typically have five vertebral scutes down the carapace’s midline and five pairs of costal scutes along the borders.
Loggerhead Biology and Behavior
The loggerhead reaches sexual maturity at around 30 years of age. There are no external differences between males and females until they reach sexual maturity. Adult males have longer tails and claws, and shorter plastrons. Males also have wider heads and wider and shallower carapaces. Their lifespan is thought to be 47-67 years.
Loggerhead turtles have a low reproductive rate. Females nest every 2 to 3 years at an average of 4 times per season. They lay between 40 and 190 eggs per clutch. Track marks measure 70 to 90 cm wide and have asymmetrical diagonal forelimb marks. The tail drag mark is usually absent.
Hatchlings have a light to dark brown carapace and light margins along their flippers. They measure 40-50 mm upon hatching.
Loggerheads spend around 85% of their day underwater. A normal dive is between 15 to 30 minutes, but they can stay under for up to four hours. Loggerheads normally rest on the bottom of the sea, remaining motionless with their eyes half closed so that they are easily alerted. In cold waters, loggerhead turtles have been recorded holding their breath for seven hours at a time. These are among the longest dives of any marine vertebrate.
Loggerhead Turtle Diet
Loggerheads have a more varied diet than any other species of sea turtle. Sponges, corals, sea urchins, squid, starfish, and even insects are on their menu. The loggerhead’s powerful jaws allow it to crush the hard shells of molluscs and crustaceans that inhabit the bottom of the ocean, such as giant clams and queen conches. They also feed on crabs, clams, mussels and other invertebrates. When they are migrating through open seas, loggerhead turtles feed on jellyfish, floating molluscs, fish eggs, and squid. Juvenile loggerheads prey on barnacles, crab larvae, fish-eggs, and hydrozoans living in Sargassum conches.
Loggerhead Habitat and Distribution
Loggerheads are distributed throughout the temperate and tropical regions of the Atlantic, Pacific, and Indian Oceans as well as in the Mediterranean Sea. They can live in water as cold as 13°C. This species may be found in pelagic areas as well as in inshore areas such as bays, lagoons, salt marshes, creeks, and the mouths of large rivers. They frequently feed on coral reefs and in rocky areas, and, like all other marine turtles, they spend their entire lives at sea.
Loggerhead hatchlings find their way to mats of flotsam (often Sargassum seaweed) in the open ocean or in shallow estuaries, where they remain for the first 7-12 years of their lives. Recent studies suggest that they spend a lot of time on the surface in their first year. At this stage, they will migrate to nearshore coastal areas to forage and grow to maturity. Like other turtles, loggerheads migrate long distances between their foraging and nesting grounds. They appear to migrate along coastlines rather than cross open waters.
Unlike other species of turtles, courtship behaviours do not take place near their nesting beaches, but along the way from the foraging grounds to the migration routes. Loggerheads nest on high-energy oceanic beaches and occasionally on estuarine shorelines. In the Northern Hemisphere, they nest between May and August, and in the Southern Hemisphere between October and March.
In the Indian Ocean, loggerhead turtles feed along the coasts of Africa, Oman, Yemen, and in the Arabian Sea. Loggerheads nest in few countries in the Indian Ocean, however, the number of nesting females is generally small with the exception of Masirah Island in Oman. There are conflicting reports of loggerheads nesting in Sri Lanka and in the Andaman and Nicobar Islands.
Loggerhead Turtles in Maldives
Though rarely spotted in Maldivian waters, the loggerhead turtle appears on the national currency, in particular on the 50 laari Maldivian coin. Locally this species is known as “boa bodu Velaa”, which translates into “big-headed-turtle”. No reports of loggerheads nesting in the Maldives exist. Furthermore, only a few photographs confirm their presence. The most recent sighting was by Olive Ridley Project staff in Haa Alif Atoll in 2017; unfortunately, the loggerhead turtle passed away from an unidentified cause.
IUCN Red List Status: Endangered (1996)
Global population estimate: Between 40,000 and 50,000 nesting adult females (2004)
Sources: Hudgins, Ali, and Mancini (2017) “Marine Turtles of the Maldives: A field identification and conduct guide”. An IUCN Publication funded by USAID.