Of the 20 species of endemic reptiles, these slow giants are the most famous. They also gave the islands their name—galápago is an old Spanish word for a saddle similar in shape to the tortoise shell. They are only found on the Galápagos and in smaller numbers on a few islands in the Indian Ocean.
The shell of a giant tortoise reveals which island its owner originates from. Saddleshaped shells evolved on low, arid islands where tortoises needed to lift their heads high to eat tall vegetation, while semicircular domed shells come from higher, lush islands where vegetation grows closer to the ground.
Of the original 14 subspecies, 10 remain, and 3 species (Santa Fé, Floreana, and Fernandina) have been hunted into extinction. The giant tortoise population has plummeted from some 250,000 before humans arrived to just 20,000 now. Today, the main danger comes largely from introduced species, but there is a comprehensive rearing program to release tortoises back into the wild, most recently on Pinta Island.
Five of the remaining subspecies are found on the five main volcanoes of Isabela, and the other species are found on Santiago, Santa Cruz, San Cristóbal, Pinzón, and Española.
There are four species of marine turtles in the archipelago. The eastern Pacific green turtle, also known as the black turtle (tortuga negra), is the most common species. Also present but rarely seen are the Pacific leatherback, Indo- Pacific hawksbill, and olive ridley turtles. Green sea turtles are rarely seen in large numbers, preferring to swim alone, in couples, or next to their young. They usually weigh about 100 kg but can weigh up to 150 kg. The females are actually bigger than the males and can grow to 1.2 meters long. The mating season, November to January, is the best time to see them. Sea turtles must come ashore to lay eggs, and females often do this as many as eight times during the mating season.
Excerpted from the First Edition of Moon Galápagos Islands.