Maybe the most famous creature Charles Darwin discovered in 1835 was the amazing Galapagos Giant Tortoise. They were huge, they were docile, and they were everywhere. It’s estimated that there were once 250,000 of them on the Galapagos Islands, and until humans discovered them, they really had no natural enemies.
Perfectly adapted
The Galapagos Giant Tortoise subspecies vary from island to island in the Archipelago, adapting perfectly to their different environments. The two major adapatations, though, have to do with shell shape – they sport either domed or “saddlebacked” shells (with an upward angle on the front of the carapace, which restricts how far UP they can extend their long necks).
It turns out that the tortoises who live on more arid islands need the flexibility to reach higher up for their favorite food, the prickly pear cactus. Those living on lush, humid islands only need to extend their necks forward to nab a delicious herbivorous dinner.
The Giant Tortoises lead a placid existence in the wild, and also in human care, sleeping up to 16 hours per day, basking in the sun, and occasionally wallowing in mud. In the wild, Galapagos finches can often be found on their shells, helpfully pecking pesky ticks from the folds of the tortoises’ skin.
The mating….not quite so peaceful
Things perk up a bit during mating season, between January and August (depending on weather), when males compete for females in a unique faceoff: it’s a neck-stretching and mouth opening contest, where the one with the longest neck gets the girl!
Mating can take hours, and is celebrated by the champion-necked males with an extremely loud roaring. Guests at the Reid Park Zoo are often confused when Ferdinand and Isabella, the Zoo’s two Galapagos tortoises, are enjoying this…um, frolic; the roaring is audible throughout the Zoo, so many people flock toward the lions – but they’re found to be fast asleep!
The females lay between 2 and 16 eggs about the size of tennis balls, burying them about 12 inches in the ground. Then they walk away – so the hatchlings are on their own, right from the start. The temperature in the nest will determine whether the babies will hatch as males or females. A few centuries ago, enough of these hatchlings survived to create a growing population of these long-lived giants. Nobody can verify the lifespan of a Galapagos Tortoise, but it has been estimated up to 170 years.
They’re endangered
Now the best estimate is that only 10,000 – 15,000 Galapagos Giant Tortoises remain on Earth.
But all hope is not lost! In 1959, the Ecuadorian government established Galapagos National Park in order to protect remaining habitat, and eggs began to be collected and incubated at the Charles Darwin Research Station on Santa Cruz Island. Other NGOs are working to protect the species. Here at home, under the guidance of the Association of Zoos and Aquariums, there are several very successful Galapagos Giant Tortoise breeding programs in accredited zoos. We can bring them back!
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