Reptiles · Sea turtles

Loggerhead Turtle

Caretta caretta (Linnaeus, 1758)
syn. Halichelys atra, Testudo caretta, Thalassochelys caretta, Thalassochelys corticata
up to 125 cmup to 200 kg1-200 mCITES IVulnerable
1043

A turtle built around its head. The skull is enormous in proportion to the animal and packed with jaw muscle, and it is a tool: loggerheads eat armored prey - conchs, clams, crabs, horseshoe crabs - and crush them outright. Nothing else in the sea turtle family works this way.

The other thing they are known for is navigation. A hatchling leaves a beach, spends years drifting in ocean currents, and comes back as an adult to nest within tens of kilometers of where it was born - and the mechanism is magnetic. Turtles read the inclination and intensity of the earth's field as a positional signature, learn their natal beach's value as hatchlings, and steer back to it decades later. Experiments in which the field around a turtle is altered send it off in the corresponding wrong direction.

Those migrations are enormous: individuals tagged in the Pacific have crossed from 🇯🇵 Japan to 🇲🇽 Mexico and back.

It is Vulnerable on the IUCN Red List and on CITES Appendix I, and its main threat is fishing gear - loggerheads drown in nets and take baited hooks meant for tuna. In this sea it is uncommon, and usually seen in open water rather than on a reef.

How to recognise it
  • very large blocky head, much bigger in proportion than in other sea turtles
  • reddish-brown shell with five pairs of scutes along each side
  • heavy body, often with barnacles on the shell
  • shell length up to 125 cm

Why it's threatened

Residential & commercial development
Housing & urban areas · Commercial & industrial areas · Tourism & recreation areas
Biological resource use
Intentional use: (subsistence/small scale) [harvest] · Unintentional effects: (subsistence/small scale) [harvest]
Human intrusions & disturbance
Recreational activities · Work & other activities
Invasive species, genes & disease
Named species
Pollution
Garbage & solid waste · Light pollution
Climate change & severe weather
Habitat shifting & alteration · Temperature extremes · Storms & flooding

Threats to Loggerheads vary in time and space, and in relative impact to populations. Threat categories affecting marine turtles, including Loggerheads, were described by Wallace et al. (2011) as:

Fisheries bycatch: incidental capture of marine turtles in fishing gear targeting other species;Take: direct utilization of turtles or eggs for human use (i.e., consumption, commercial products);Coastal Development affecting critical turtle habitat: human-induced alteration of coastal environments due to construction, dredging, beach modification, etc;Pollution and Pathogens: marine pollution and debris that affect marine turtles (i.e., through ingestion or entanglement, disorientation caused by artificial lights), as well as impacts of pervasive pathogens (for example fibropapilloma virus) on turtle health;Climate change: current and future impacts from climate change on marine turtles and their habitats (increasing sand temperatures on nesting beaches affecting hatchling sex ratios, sea level rise, storm frequency and intensity affecting nesting habitats, etc.).The relative impacts of individual threats to all Loggerhead subpopulations were assessed by by Wallace et al. (2011). Fisheries bycatch was classified as the highest threat to Loggerheads globally, followed by coastal development and human consumption of eggs, meat, or other products. Due to lack of information, pollution and pathogens was only scored as affecting three subpopulations and climate change was only scored for two subpopulations. Enhanced efforts to assess and reduce the impacts of these threats on Loggerheads—and other marine turtle species—should be a high priority for future conservation efforts. More detailed information at regional level can found in the specific subpopulation assessments.

Threat classification from the IUCN Red List.

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Last Update: August 15, 2026