There are seven species of sea turtles on Earth: green sea turtles, leatherback sea turtles, flatback sea turtles, loggerhead sea turtles, hawksbill sea turtles, Can's ridley turtles and olive ridley turtles. Sea turtles typically live between 30 and 50 years, with documented turtles living as long as 150 years. While we know that all sea turtle species have long lifespans, the upper limit of their potential natural lifespan remains a mystery to scientists.

Of the seven species of sea turtles on Earth, hawksbill turtles have the shortest lifespan, at 30 to 50 years, while green sea turtles have the longest lifespan, up to 80 years or more. The average lifespan of both the largest and smallest sea turtles—the leatherback and the Cannellini turtle—is 45 to 50 years.

sea turtle life cycle

born

A sea turtle's life begins when a female sea turtle nests and lays her eggs on a beach, usually close to where she was born. She builds nests two to eight times per season, laying approximately 100 eggs per nest. The eggs are vulnerable to predators such as birds, mammals and fish. After six to eight weeks, the surviving hatchlings emerge from their shells (called "shelling") and emerge from the sand toward the water.

lost years

It is estimated that only 1 in 1,000 to 1 in 10,000 larvae survive to undergo the next stage of life: the high seas stage. This period, which lasts from 2 to 10 years, is also known as the "lost years" because sea turtle activity at sea is difficult to monitor. While scientists can tag sea turtles, the transmitters used are often too large for the young creatures. In 2014, a team of researchers from Florida and Wisconsin used smaller equipment to track the "lost years" of hatchlings they raised for a few months and then released. They concluded that hatchlings go to sea to avoid predators and follow warm surface waters to support their growth.

adulthood

The turtle slowly grows up. They take 15 to 50 years to reach reproductive maturity. As adults they forage in coastal waters and migrate to beaches to mate. Only females come ashore to nest, a process that occurs every two to five years.

Like birds and fish, sea turtles rely on the Earth's magnetic field to return to their birthplace. Their migration can be lengthy. In 2008, a leatherback turtle was tracked 12,774 miles from Indonesia to Oregon. Females are known to build nests until they are 80 years old.

die

Sea turtles often die from predation and human-related causes. Their main predators are large fish such as sharks, killer whales and groupers. They also face dangers from poaching, entanglement in fishing gear, pollution, marine debris such as plastic, and climate change. Rising sea levels and increased storm activity threaten nesting sites. Due in large part to these man-made threats, most sea turtle species are endangered.

How long can sea turtles live?

The title of "oldest sea turtle" remains unclaimed, adding to the species' mystique. Accurately determining the lifespan of sea turtles is particularly difficult because sea turtles often live longer than the duration of most studies. Once a turtle is tagged, satellite data transmission typically only lasts 6 to 24 months. Sea turtles, meanwhile, can live for decades.

To make things even murkier, there is no scientifically accepted way to use a turtle's appearance to determine its age. Scientists often analyze the skeletal structure of dead sea turtles to estimate age.

One of the oldest known sea turtles is a green turtle named Myrtle, who has lived at the Cape Cod Aquarium for more than 45 years and is estimated to be 90 years old. However, some turtles can live 100 or even 150 years, according to Carol Haley, assistant curator of fish at the Tennessee Aquarium.

Over the past few decades, some turtles may have lived longer than this estimate. In 2006, Li Chengtang, director of the Guangzhou Aquarium in China, said the oldest turtle on site was "determined to be about 400 years old based on shell testing by a taxonomy professor." In another news about an elderly sea turtle in the Philippines, reports say that a sea turtle close to 200 years old was found in a fish pen and was taken to the Bureau of Fisheries and Aquatic Resources.

Why do sea turtles live so long?

Sea turtles have been on Earth for over 100 million years. To put things into perspective, the dinosaurs became extinct about 65 million years ago, and early human ancestors began walking on two legs about 4 million years ago.

Research shows that a key reason for sea turtles' longevity is their slow metabolism, or the rate at which they convert food into energy. According to a 2011 study in the Journal of Experimental Biology, metabolic rates play a key role in sea turtle health because they control "the fitness of individuals" and "ultimately determine population structure and size." Animal metabolism is sometimes described as the "fire of life." Typically, the slower the burning rate, the longer the life of the fire or organism. Turtles have slower metabolism and growth, so they live longer.

Green sea turtles can slow their heartbeats to 9 minutes between beats. This characteristic allows them to carry out long feeding dives of up to five hours. In stark contrast, a fast hummingbird's heart beats up to 1,260 times per minute and may feed as often as every 10 minutes. Hummingbirds have a much shorter lifespan than sea turtles, only three to five years.

Although sea turtles continue to face numerous threats, scientists and researchers will not be intimidated. Perseverance in conservation efforts allows these great divers to continue to challenge the limits of ocean longevity.

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