Loggerhead sea turtle

The loggerhead sea turtle, known scientifically as Caretta caretta, is a massive marine reptile.

It belongs to the family Cheloniidae, which includes most living sea turtles except the leatherback. This species is the largest hard-shelled turtle in the world. It is also the second-largest extant turtle overall. Loggerheads are found in a cosmopolitan distribution across the globe. This means they live in many different parts of the world. They inhabit the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean Sea.

The anatomy of a loggerhead is built for life in the ocean. Their shell consists of two main parts: the carapace and the plastron. The carapace is the upper shell, which is reddish-brown and divided into large plates called scutes. There are usually 11 or 12 pairs of marginal scutes around the edge. Five vertebral scutes run down the middle, and five pairs of costal scutes border them. The plastron is the pale yellow underside. The two parts connect at the sides via the bridge. While their shell provides armor, loggerheads cannot retract their heads or flippers inside it.

Loggerheads have unique physical traits that help them survive. They are omnivorous and primarily eat bottom-dwelling invertebrates. Their large, powerful jaws are perfect for dismantling prey. Behind each eye, they have lachrymal glands. These glands help maintain osmotic balance by removing excess salt from the ocean water they swallow. When this salt is excreted, it can look like the turtle is crying.

Furthermore, adults show sexual dimorphism, meaning males and females look different. Adult males typically have thicker tails, shorter plastrons, wider heads, and wider carapaces than females.

The history of the loggerhead is very long. They appeared about 40 million years ago and likely descended from a single ancestor during the Cretaceous period. In 1758, Carl Linnaeus gave them the name Testudo caretta. Later, in 1873, Leonhard Stejneger introduced the name Caretta caretta. About three million years ago, the emergence of Central America changed ocean currents. This created coldwater barriers that isolated Atlantic and Pacific populations. This isolation led to distinct genetic populations. For example, Mediterranean loggerheads are generally smaller than those in the Atlantic.

Life cycles for these turtles involve many years of waiting. A loggerhead reaches sexual maturity between 17 and 33 years of age. Their lifespan is estimated to be between 47 and 67 years. Females lay an average of four egg clutches in their lives. After laying, they become quiescent, meaning they produce no more eggs for two to three years.

Florida is a major site for this activity, hosting over 67,000 nests annually. In the Pacific, the Japanese Islands are vital, as 40% of nearby loggerheads visit Yakushima Island. One famous female named Adelita was the first animal ever tracked across an entire ocean basin.

Despite their size, loggerheads face many dangers. They are currently considered a vulnerable species by the IUCN. In the United States, nine population segments are protected by the Endangered Species Act of 1973. Five of these are classified as endangered, while four are threatened. One major threat is the loss of nesting habitat due to coastal development. Human disturbances, like coastal lighting, can disorient hatchlings as they emerge.

They also face risks from untended fishing gear and suffocation in fishing trawls. To help, some fishers use turtle excluder devices, which provide an escape route for the turtles.

Protecting the loggerhead requires global effort. Because they roam such vast areas, no single country can manage them alone. They connect different ecosystems, from the nurseries of the Mediterranean to the foraging grounds of the East China Sea. Their survival depends on international cooperation to protect nesting beaches and reduce human-caused mortality. By understanding their biology and history, we can better support their recovery in our oceans.