This past October, I went to the New England Aquarium in Boston for the first time with some visiting friends. You should go if you’ve never been; it’s a solid aquarium! One of the coolest parts was this giant tank in the center. We’re talking four stories tall. 40 feet wide. 200,000 gallons of salt water. It’s a large tank.
Inside the Giant Ocean Tank, as it’s called, was hundreds of Caribbean reef animals. But out of all the amazing fishes and eels, one creature was the undisputed queen: Myrtle the green turtle.
Myrtle was (and still is!) glorious. According to the aquarium, she is more than 90 years old and weighs more than 500 pounds. Myrtle owned that tank and she knew it. I loved watching her swim around and chill at the top of the Giant Ocean Tank, basking in the adoration of her fans.
As I’ve done more research, I’ve found that Myrtle isn’t the exception: green turtles (Chelonia mydas) are pretty awesome in general. Between their large bodies, long lives, and vegetarian habits, I’ve become a fan of these creatures.
- What is a sea turtle anyway?
- Sea turtles are reptiles that live in, you guessed it, the sea. There are seven different species of sea turtles: green, loggerhead, Kemp’s ridley, olive ridley, hawksbill, flat black, and leatherback. All of these species are highly migratory and travel across the oceans, coming to shore to bask or nest. Sea turtles are also ancient: they have been swimming around the earth for the last 100 million years!
- A quick note on sea turtle shells
- First order of business: turtles cannot come out of their shells. Turtle shells are fused to a turtle’s spine.
- Second order of business: sea turtles can’t retract their heads into their shells like land turtles can. It just won’t happen.
- In all sea turtle species except the leatherback, the shell is covered with horny plates made of keratin (the same stuff that makes your fingernails). These plates are called scutes and are firm but flexible. The number and pattern of the scutes differ between species and can be used for species identification.
- Now leatherbacks don’t have this horny plates. Instead, they have a thick, rubbery, oil-suffused skin. This skin is a great insulator and keeps the leatherback warm, allowing them to go into colder waters than other sea turtles.
- Large beauties
- Here’s why I told you about sea turtle shells: green turtles are the largest hard shell sea turtles. The only sea turtle larger is the leatherback, which, as you recall, has a thick skin instead of a hard shell. So if you want to base your classification of “largest” for only sea turtles who have hard shells, then green turtles win! (Sorry, leatherbacks). And as I saw with Myrtle, green turtles are large. Typical adults are 3 to 4 feet long and weigh 300 to 350 pounds. Males and females are about the same size and there is little sexual dimorphism (so they look pretty much the same). However, you can tell males and females apart by looking at their tails and front claws. Adult males have longer, thicker tails, since their reproductive organ is situated at the base of their tail. Males also have elongated and curved claws on their front flippers which may help them hold onto the female’s shell during mating.
- Why green?
- If you just looked at their shell, you may be confused on how green turtles got their name. Their shell, as the picture above demonstrates, tends to be olive-brown with dark streaks on top. When predators look down from above the green turtles, this coloration helps them blend in with the ocean depths. Their bellies tend to be much lighter (yellow to white). This also serves as camouflage, as the light coloration blends in with the brighter sea surface when viewed from below. So: why are green turtles called green turtles if their shells aren’t green? The answer is fat! Green turtles get their name from the greenish color of their cartilage and body fat. Next obvious question: why is their fat green? Well, just like flamingos turn pink from their diet, green turtles have greenish fat due to the vegetation in their diet.
- Algae lawnmowers
- Out of all the sea turtles, green turtles are the only ones that are primarily vegetarian in adulthood. They eat seagrasses and algae (although a few rebels will eat prey animals like jellyfish once in a while). According to WWF, green turtles function much like lawnmowers: their lower jaw is serrated, allowing them to crop the seagrass. That seagrass is then digested quickly and the recycled nutrients are returned to the ecosystem for plants and other animals to use. Green turtles are therefore a vital part of keeping the ocean seagrass beds healthy and thriving.
- Long life
- It’s unknown exactly how long green turtles live, but people think they live for at least 70 years in the wild and may possibly live to reach 100. Myrtle herself is over 90 years old. Green turtles also take a while to reach maturity: females won’t start reproducing until they are around 25 – 35 years old. Green turtles are the slowest sea turtle to mature, potentially because their diet lacks high amounts of protein.
- Beach babies
- Green turtles (like all sea turtles) spend most of their life swimming around in the ocean. But about every 2 years, green turtles will migrate hundreds to thousands of kilometers from their foraging grounds to their nesting beaches. Females nest on the beaches where they themselves hatched. Once they reach their natal beaches, the female green turtles will start nesting. They pull themselves out of the water at night, dig a nest in the sand, and lay about 110 eggs. They will keep nesting every two weeks for several months before returning to the open ocean.
- The eggs will hatch after about two months of being buried in the sand. Now comes the dangerous part: once they dig themselves out, the new hatchlings have to dash to the water. Sea turtles in general are not great on land, and this dash can be fatal if predators are waiting to nab the hatchlings. Humans have also made getting to the ocean much more difficult. Ideally, the hatchlings know where the ocean is by navigating towards the the brightest horizon. This SHOULD be the horizon over the ocean. But with human development, there are often lots of other bright things on the horizon (i.e., street lamps, signs, headlights…). This can confuse the hatchlings and lead them in the wrong direction, away from the ocean and likely to their death. An easy way to protect green turtles and other sea turtles is to reduce lights along the beach front during nesting season. Turn off the lights! Help the hatchlings not get lost!
There you have it. Green turtles are pretty cool. Really not much more to say other then, “I like turtles,” and I hope you do, too.