Of all the unusual creatures on the Galápagos Islands, the most impressive are the huge Galápagos tortoises. They were once so plentiful that ships stopped by to load up as many as 700 live animals. Since one tortoise could provide 200 pounds of meat, this living cargo ensured fresh meat for months. Unfortunately, even in Darwin's day the heavy harvest was taking its toll, and their numbers had already been greatly reduced.

Darwin was startled to discover that each Galápagos island was "inhabited by a different set of beings." For example, the tortoises on each island were slightly different. Darwin reported that by looking at a tortoise's shell, the colony's vice governor "could at once tell from which island any one was brought."

The Galápagos Giant Tortoise (Geochelone elephantopus)

©K. Frey/CBC/AMNH

Go To It, Charlie!

Darwin was fascinated and amused by the "immense" Galápagos tortoises. They were so large that he could not resist climbing on top for a ride.

"I frequently got on their backs, and then giving a few raps on the hinder part of their shells, they would rise up and walk away; but I found it very difficult to keep my balance.

Separated by the Sea

Minor differences distinguish the Galápagos tortoises on each island. But there are also two basic types, adapted for different feeding habits.

Tortoises from Pinzn Island (formerly Duncan Island) are "saddle-backed," meaning that their shells rise in the front, like a saddle. This adaptation makes it easier for them to lift their necks and feed on taller cactus.

Tortoises from Santa Cruz (formerly Indefatigable Island) have "dome-shaped" shells. Animals with these shells live on islands where most of the vegetation is close to the ground, making it unnecessary to raise their heads to feed.