Some people would love to live for over 100 years. Why this may not always be possible for humans, it is quite common for the Galapagos giant tortoises. The oldest reported giant tortoise is believed to have been Harriet, who is estimated to have been at least 176 years old when she died in 2006 while on display at the Australia Zoo in Brisbane, Australia. Handpicked by Charles Darwin himself when she was approximately five years old, even he could not have imagined the possibility of her outliving her human caretakers to such a degree (Franklin 45). Her longevity however, is not unique. The giant tortoises of the Galapagos Islands have repeatedly demonstrated an increased lifespan due to their unique body structure, diet, and lifestyle.
The Galapagos Islands provide a habitat to one of only two known remaining groups of giant tortoises in existence today (Alderton 151). Scientists speculate that smaller tortoises drifted to the Galapagos Islands where they found plentiful vegetation and practically no indigenous predators. Over time they evolved into the humble, lumbering giants that exist today. The phenomenon of gigantism evolution is seen in many island ecosystems where there is no need to hide from predators and no competition for food (Orenstein 108). This lack of predation would not last forever. In the nineteenth century the Galapagos Islands were frequented by sailors and fishermen who coveted the fresh meat available in abundance from the giant tortoises. They were prized for their quantity and ability to be stored for months on end without food or water (Hoagstrom 1623). This adaptability for drought stricken times could be a direct link to their evolution of body structure and greatly enhance their capacity for longer lives.
According to Franklin, and perhaps their most distinguishing feature, a tortoises’ shell is composed of three major sections. The upper part of the shell is known as the carapace. Connecting the carapace to the plastron, the bottom half of the shell, is the bridge. The shell’s main function is for protection and its shape is unique to the type of individual tortoise species. The Galapagos’ tortoise derives its name from early Spanish explorers who compared the islands and the saddle shape of the tortoise’s shell to Galapago, a particular Spanish term for a saddle with an upturned front (Franklin 14, 127). As an indication of their potential, they have been known to weigh up to 250 kg and have a measurement of the curve of their carapace (top of shell) over 150 cm. (Jackson 102). Male tortoises are typically even larger than the female gender (Franklin 126). Tortoises’ limbs are heavily scaled and resemble huge ponderous columns used to support its heavy body. They are very functional for their terrestrial lifestyle. Although a tortoise has a reputation for being slow and lumbering, they can increase their speed to some degree and cover quite a distance in a relative amount of time.
A tortoise breathes by...