How Long do Tortoises Live and Why are They so Important?

Tortoises are Important to Ecosystems

There was a great deal of celebration when Jonathan the Seychelles Giant Tortoise turned 190 years old in 2022.

Although his exact date of hatching isn’t known, he was fully mature when he was taken from his home on the Seychelles Islands on the East coast of Africa. A Giant Seychelles reaches adulthood at about 50 years of age. That would place his hatching date sometime in the 1830s.

However, some of his caregivers believe that he’s actually much older than that.

Jonathan is celebrated for being the world’s oldest-known tortoise, but he’s not alone. Tortoises all over the world are known for their long stay on this Earth. This is more important than we may ever fully know because tortoises are one of the few animals on earth that have the power to create, change, protect, and even destroy a habitat. 

That’s a big thing for such a slow creature, and it’s the reason why Galapagos tortoise projects are very a very big deal to tortoise protection projects are very big in Galapagos islands. It turns out that keeping this amazing species alive for hundreds of years could have some profound benefits to ecosystems. 

How Long do Tortoises Live?

It can be difficult to tell the age of tortoises because these creatures routinely outlive most human beings. Moreover, hatching dates for wild tortoises are rarely known. Scientists place the average lifespan of a tortoise at anywhere between 80 and 150 years. Some are even thought to be as much as 250 years old.

Although these are all estimates, they are far from wild guesses. Tortoises provide several different clues about how long they’ve been around.

How to Tell a Tortoises Age

It is much easier to track the age of a captive tortoises because their conditions can be monitored and scientists generally have a lot of information to go on. This was the case with Jonathan the Seychelles giant tortoise.

When tortoises are not monitored, other methods are required to help scientists determine the age of a tortoise.

• The Shell: Scientists can study a tortoise’s shell for clues. Older individuals will have smoother, less detailed shells than younger tortoises. This is because they’ve experienced decades of weather and wear-and-tear. However, this may not be so in tortoises who have lived in the shelter of captivity.
• Behaviour: Like most creatures, older tortoises will be less energetic than they were when they were young. Scientists can watch a tortoise to see how much time it spends resting. The more rest periods a tortoise takes, the older it likely is (looks like we might have more in common with tortoises that we originally thought).
• Tagging: Scientists have also made a study of the aging process of the tortoise. Scientists catch wild tortoises at less than two years old. They release it back into the wild with a mark on its shell so they can recognize it later. When they catch it again, they can make observations and notes about how it’s changed as it’s aged. This data can be used to estimate the growth of other individuals.
• Fungal Growth: Wild tortoises often have fungal growth on their shells. How much fungus is present and what kind can provide clues as to how long a tortoise has been around. This method is most accurate when used along with other age-determining methods.
• Bones: Scientists can study the layers of growth in a tortoise’s bones for a pretty accurate age estimate. Of course, this study can only be done on deceased tortoises since it requires dissection of the animal to retrieve the bones.

All of these methods help scientists tell the age of tortoises. Perhaps the more important questions, however, are what allows them to live that long.

Why Do Tortoises Live So Long?

Researchers have developed several theories as to why tortoises live so long and age so slowly. This includes genetic variances, the metabolism of tortoises, it’s shell, as well as its environment.

• Genetic Variances: Scientists have discovered a genetic variance in tortoises. This difference provides an enhanced immune system. It also provides them with the amazing ability to suppress cancer. This genetic difference simply makes it less likely that a tortoise will die of illness.
• Continued Growth: Tortoises never stop growing through their lives. Research finds that species that continue to grow tend to be around longer on average than those that don’t. This is because of the cell renewal and regeneration which continues as long as growth is happening.
• Metabolism: The slower metabolism of a tortoise allows them to burn energy at a slower rate. They breathe more slowly and their heart rate is lower than many other animals. This allows their inner organs to work more slowly, and last longer.
• Shell: Scientists have observed that animals with shells will often tend to live longer. This hard armour protects them from predators. Since they don’t have to work at protecting themselves, they have more energy to devote to living longer.
• Environment: Studies have shown that turtles in captivity do not experience a higher mortality as they age, as those living in the wild do. In captivity, they don’t have to spend energy in foraging for food or water. That leaves more energy for replenishing their cells.

Whatever causes their long lives, it’s allowed them to stay around long enough to be one of the most important species on earth.

Why are Tortoises Important?

Tortoises are all around us. They exist on every continent except Australia and the Antarctic. It’s not surprising, then, that they’ve made their way into the hearts of so many cultures around the world.

The most famous instance of this, of course, is Aesop’s ancient Greek fable of the Tortoise and the Hare.

The tortoise has appeared in cave drawings, ancient literature, and in legends and creation stories all around the world. India, China, and Indigenous North America all have myths depicting the tortoise helping to build the world or holding it up on its back. The tortoise is also featured in the ancient stories of Greece, ancient Egypt, and Polynesia.

However, their most important place in the modern world is in their role as a keystone species.

Tortoises are a Keystone Species

The Galapagos Tortoise has been identified as a keystone species. This is any species that has a significant impact on its environment. When a keystone species is removed, the environment is altered substantially.

Specifically, the Galapagos Tortoise is known as an ecosystem engineer. Ecosystem engineers are animals that create, change, or protect a habitat. Tortoises make their habitat livable for other creatures, so its absence can even destroy a habitat.

Tortoises disperse and germinate seeds while grazing on plants. They trample down vegetation, opening up new spaces for fresh plants to grow using these seeds.

Tortoises are Endangered

Isla Santa Fe, one of the Islands in the Galapagos, was stripped of its population of native tortoises in the mid-1800s. Between their loss and the introduction of feral goats, the island suffered severe damage to both plants and soil.

The goats were removed by the 1970’s. However, the island ecosystem was unable to recover until a new population of tortoises from another island was released in Isla Santa Fe. Both local plant and animal life began to thrive again.

It’s through events like this that we can see how important the tortoise truly is to our world. This is also why it’s so important that every effort is put into projects designed to protect them.

Galapagos Tortoise Projects

Since Charles Darwin first set foot on the Galapagos Islands in 1835, there has been a dramatic change. It was once a haven of biodiversity that allowed Darwin to begin developing his theory of evolution. He described it as “very remarkable: it seems to be a little world within itself; the greater number of its inhabitants, both vegetable and animal, being found nowhere else.”

Today, Darwin would be disappointed.

The population of giant tortoises that once thrived all over the Galapagos is now down to 10% of its former numbers. However, they’ve also been the subject of one of the most successful and inspiring conservation efforts in history.

In the last six decades, some 9000 tortoises have been raised in captivity and returned to the Galapagos wilderness. Once free, they’ve healed the damaged ecosystem and begun the work of repopulating their own species.

Why are Galapagos Tortoise Projects Important?

Galapagos Tortoise Projects are Important because there are more species of tortoises in the Galapagos than anywhere else on Earth. The Galapagos population is critical to understanding these creatures. What scientists learn there can even have a positive impact on repopulation projects of other species around the world.

Tortoises are Making a Strong Comeback

Among the most amazing and exciting accomplishments is the recovery of the Espanola Giant Tortoise. Due to hunting and invasive species, these tortoises were reduced to only 15 surviving species. Through the conservancy program, the population has now increased to over 2300 individuals.

Most recently, 136 young tortoises were rewilded to their ancestral home on Isabela Island in the Galapagos. These tortoises will live for a hundred years or more. As a keystone species, they represent 136 opportunities to restore the ecology of the Galapagos Islands for the next century and beyond.

That’s an exciting and hopeful promise for the future of our planet.