There are seven species of sea turtles on Earth: green sea turtles, leatherback sea turtles, flatback sea turtles, rump sea turtles, hawksbill sea turtles, olive ridley sea turtles, and olive ridley sea turtles. Sea turtles typically live between 30 and 50 years, with some recorded lifespans reaching 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, ranging from 30 to 50 years, while green sea turtles have the longest, living up to 80 years or more. The largest and smallest sea turtles—leatherback sea turtles and olive ridley sea turtles—have an average lifespan of 45 to 50 years.
Sea turtle life cycle
born
The life of a sea turtle begins when the female builds a nest and lays her eggs on a beach, usually near where she was born. She nests two to eight times per season, laying about 100 eggs in each nest. These eggs are vulnerable to predators such as birds, mammals, and fish. After six to eight weeks, the surviving hatchlings emerge from the sand (a process called "hatching") and head for the water.
Lost Years
It is estimated that only one in a thousand to one in ten thousand hatchlings survive to reach the next stage of their lives: the high seas stage. This period, lasting two to ten years, is also known as the "lost years" because the turtles' activities at sea are difficult to monitor. While scientists can tag the turtles, the launchers used are often too large for young creatures. In 2014, a team of researchers from Florida and Wisconsin used smaller equipment to track the "lost years" of hatchlings they had raised for several months before releasing them. They concluded that newly hatched turtles venture out to sea to avoid predators and follow the warm surface waters to support their growth.
Adulthood
Sea turtles grow slowly. It takes them 15 to 50 years to reach reproductive maturity. Once adults, they forage in coastal waters and migrate to beaches to mate. Only females come ashore to build nests, a process that occurs every two to five years.
Like birds and fish, sea turtles rely on Earth's magnetic field to return to their birthplace. Their migrations can be long. In 2008, a leatherback sea turtle was tracked from Indonesia to Oregon, a journey of 12,774 miles. It is understood that females nest before the age of 80.
die
Sea turtles frequently die from predation and human-related causes. Their primary 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. Most sea turtle species are endangered to a large extent due to these human threats.
How long can a sea turtle live?
The title of "oldest sea turtle" remains unclaimed, adding to the species' mystique. Accurately determining a sea turtle's lifespan is particularly difficult because they often exceed the duration of most studies. Once a turtle is tagged, satellite data transmission typically lasts only 6 to 24 months. Meanwhile, turtles can live for decades.
What makes things even more complicated is that there is no scientifically accepted method to determine a sea turtle's age based on its appearance. Scientists often analyze the skeletal structure of dead sea turtles to estimate their age.
One of the oldest known sea turtles is a green sea turtle named Myrtle, which has lived at the Cape Cod Aquarium for over 45 years and is estimated to be 90 years old. However, according to Carol Haley, assistant curator of fish at the Tennessee Aquarium, some sea turtles can live to be 100 or even 150 years old.
In recent decades, some sea turtles may have lived longer than this estimate. In 2006, Li Chengtang, curator of the Guangzhou Aquarium in China, stated that the oldest sea turtle on site was "approximately 400 years old, determined by shell tests conducted by a taxonomy professor." Another news report from the Philippines about an elderly sea turtle stated that a nearly 200-year-old turtle was found in a fishpond and taken to the Department of Fisheries and Aquatic Resources.
Why do sea turtles live so long?
Sea turtles have existed on Earth for over 100 million years. In the long term, dinosaurs went extinct about 65 million years ago, and early human ancestors began walking on two legs about 4 million years ago.
Research suggests 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 published in the *Journal of Experimental Biology*, metabolic rate plays a crucial role in sea turtle health because it controls "individual health status" and "ultimately determines population structure and size." Animal metabolism is sometimes described as the "fire of life." Generally, the slower the burning process, the longer the fire, or the organism, lives. Sea turtles have a slow metabolism and grow slowly, thus contributing to their longer lifespan.
Green sea turtles can slow their heartbeats to a 9-minute interval between each beat. This characteristic allows them to dive for extended periods, sometimes up to five hours, to feed. In stark contrast, fast hummingbirds have hearts that beat up to 1,260 times per minute and may feed every 10 minutes. Hummingbirds also have much shorter lifespans than sea turtles, only three to five years.
Despite the numerous threats that sea turtles continue to face, scientists and researchers are not deterred. Unwavering conservation efforts allow these amazing divers to constantly push the limits of ocean longevity.
