Normally, asking someone, “How old are you?” might be considered a little rude. But when it comes to the creatures of the reef, the answers are simply too intriguing not to ask.
We’ve all had those moments while snorkeling when a wrinkled, barnacle-encrusted sea turtle glides gracefully past, making you think, “That dude has seen some things.“. Or perhaps you’ve drifted over a coral colony stretching for tens of meters and found yourself wondering, “Were you alive when the dinosaurs still roamed the Earth?“. Well, in this blog, we’re going to ask that nosy question “How old are you?” to some of our favorite residents of the reef. The answers might just leave us all feeling a little younger.
Giant Barrel Sponge
On tours, every now and again, I encourage our guests to swim towards deeper water and peak over the edge of the shallow plateau we are snorkeling over. One of the most prominent things you will likely see are these giant barrel sponges that can grow to be so large that you could easily fit inside one. When it comes to age, these sponges absolutely knock it out of the park… and right into outer space.
Giant barrel sponges tend to grow anywhere between a few millimeters to a couple of centimeters a year. Depending on their position on the reef they will have more or less nutrient rich water flow through them which correlates with their growth rate. By taking repeated photographs of their growth over time scientist have estimated that many of these sponges are 100s of years old. And most impressively, the oldest giant barrel sponge measured to date is over 2000 years old!!!
If this has you wondering how old your favorite sponge is, Dr Joseph Pawlik has made it easy for us to date sponges with his Sponge Age Calculator. Using a flexible measuring tape, measure the height, diameter of the opening of the sponge, and the circumference of the base (of course only attempt this if you are confident with your buoyancy and duck diving skills, taking care not to touch the sponge). You can pop your measurements in the Dr Pawlik’s calculator HERE and find out how old the sponge is!
One of the largest animals I have had the pleasure of snorkeling alongside is the enigmatic whale shark. To me, the whale shark is a bit of a paradox. I can never decide whether I see them as wise wanderers of the ocean, with their astonishing size and graceful tail swings, or as slightly goofy, oversized fish with their wide smiles, friendly eyes, and nonchalance. Wise or not, an animal of that size always leaves you wondering just how old they are.
Whale sharks are, of course, the largest fish in the sea, with the largest ever recorded measuring an incredible 18 meters in length. However, despite their enormous size, surprisingly little is known about them. Most whale shark encounters happen when they swim near the surface to feed on plankton. But when it comes to other behaviors, such as mating and giving birth, whale sharks prefer a little privacy, disappearing out of sight, into the deep blue.
What we do know is that whale sharks definitely live for more than 50 years and most likely reach ages of between 100 and 150 years! To put that into perspective, an elderly whale shark swimming around today may have lived through both World Wars, been alive before electricity became common in homes, and even been around when we rode around in horse drawn carriages.
Scientists estimate the age of whale sharks by counting growth rings in their vertebrae, much like counting the rings of a tree. Their long lifespan also makes them especially vulnerable to extinction, as they don’t reach sexual maturity until around 30 years old. These gentle giants remind us that sometimes the secret to a long life is to slow down and take it easyyyy!
Sea turtles
Sea turtles have definitely earned their place in this blog. Their ancestors have been around for more than 150 million years, living alongside the dinosaurs and surviving the mass extinction event that wiped thousands of species from the planet.
From the very beginning of a tiny turtle’s life, it must dodge countless predators and swim thousands of kilometers before reaching adulthood. Safe to say, turtles are tough cookies! Yet these trials and tribulations don’t seem to faze them. When we are lucky enough to encounter one snoozing on the reef or gracefully swimming off into the blue, they embody a wonderfully chilled-out attitude that is hard not to envy.
According to scientific research, the longest-living sea turtle species are the green turtle and the loggerhead turtle, both of which can live for more than 80 years. Other species, such as the hawksbill and leatherback turtles, have been found to live for up to 50 years.
However, animals with such long lifespans are incredibly difficult to study, as they can outlive the very humans attempting to research them. Therefore, some speculation remains that, much like humans, there may be turtles out there that have lived to celebrate their 100th birthday.
Final Thoughts
The oldest known reef fish is a midnight snapper found off the coast of Western Australia, which was estimated to be 81 years old! The ocean is a treasure trove of endless discovery and enquiry, constantly revealing new stories, making every snorkeling experience unique. By protecting and conserving our oceans, we can continue to learn from these remarkable animals and uncover the many secrets that the ocean still holds.
