Giant Tortoises
Land Lizards
Insects
Plant Life
Birds
No creature is as firmly linked in the public mind with the archipelago
than the giant tortoises endemic to all but a handful of the Galápagos
islands. (The Bishop of Panama himself set the precedent, naming
the islands he discovered in 1535 after these giant reptiles.) Ever since, the fate of the islands seems
eerily linked to the fate of its largest denizens. Their abundance
and seeming endlessness paralleled the bountiful (if thoughtless)
harvests of the whaling era, while their current endangered status reflects
the pressures the islands suffer under. They have become emblematic
of survival in the Galápagos: during the fishermen's uprisings
of the past several years, a common complaint was that scientists
care more for tortoises than people. Some wild tortoises have
actually been slaughtered on Isabela and other islands, almost
certainly by irate local fishermen. (See Issues).
Leaving aside the political question, the Galápagos tortoise (Geochelone elephantopus) is an amazing creature indeed. While there is only one species, there were at least 14 varieties, each in some ways distinctive to the island of its residence. Darwin records that the vice-governor of the islands claimed he could tell which island any particular tortoise came from by the its shell, and he may not have been bragging. Not only are the patterns on the back of the shell slightly different, but the overall shell shape is too.
There are two major shell designs. The upper half of the shell is called the carapace,
as distinct from the plastron, or lower half. The domed
carapace is found on larger varieties from Santa Cruz and the
Alcedo Volcano on Isabela, where the large browsing tortoises
feed on the relatively lush vegetation. The saddle-back
carapace found on the Española and Pinta varieties allows
for the long neck to emerge to allow feeding on the hard-to-reach
vegetation of the drier islands. Intermediate types bridge the
two extremes, all evolving from the prototypical Galápagos
tortoise which first colonized San Cristóbal.
Of the 14 original varieties, those from Fernandina, Floreana and Santa Fé are extinct, and one more on the verge (Pinta, home of Lonesome George). Although the separate varieties of Pinzón, Española, Santiago, Santa Cruz are still found, along with the five varieties inhabiting the volcanic heights of Isabela, all native tortoises are still at risk. Introduced species not only raid tortoise nests and kill the young, but more importantly, feral goats, domestic cattle and other animals consume the vegetation that have provided sustenance and shelter for the tortoises for a million years. Scientists believe a quarter million tortoises inhabited the Galápagos prior to the arrival of humans; now there are perhaps 15,000.
Tortoises are vegetarian, eating large quantities of prickly pear (Opuntia) cactus and fruits, bromeliads, water ferns, the so-called poison apple (Hippomane mancinella) and other native species. They have tremendous water storage capacities, being able to store enormous quantities which enable them to survive the long arid season. One of the reasons they were so popular with whalers and sailors was their ability to live for up to a year without food or water -- they were stored upside-down in the bilge like so many 500-pound barrels, ready for slaughter when fresh meat was on the menu.
Another much-fabled aspect of tortoises is their longevity. In captivity, they mature in about 20 to 25 years. Mating is arduous, and nests take several days to dig. Only two to 16 eggs are laid once a year (compared to the 600 a sea turtle may lay in a season). Their wide dispersal in the archipelago -- from San Cristóbal in the east to Fernandina in the west, from Pinta in the north to Floreana in the south -- is probably due as much to their toughness and longevity. No one knows for certain, but it is thought these giant tortoises live over 200 years in the wild. By way of illustration, a fully grown giant tortoise from Madagascar (G. radiata) was presented to the Queen of Tonga by Captain Cook in the 1770s. This tortoise died in 1966.
It is entirely possible, on your visit to the Galápagos,
that you may meet one of the same tortoises who greeted Charles
Darwin a mere 161 years earlier -- perhaps the slow, patient one
he rode like a pony, whooping with joy.
