The Galapagos Islandsare well-known for their variety and abundance of various forms of primeval reptiles, most of which arenít founed anywhere else on earth. Out of 22 species of tortoises
, 90% are endemic to the archipelago.
Giant tortoises are the big stars in the pantheon in the Galapagos Islands. Numbering some 15,000 and weighing up to 250 kg [550 lb
], these are the biggest tortoises in the world. It is estimated that between two and three hundred thousand were killed or captured as sources of fresh meat by whalers and sealers or taken away by collectors in the 18th and 19th centuries.
Fourteen subspecies of giant tortoise inhabited the archipelago when it was discovered in 1535. Today, only five subspecies are numerous enough to be considered safe, five are threatened and three are extinct. One subspecies has just one surviving individual, Lonesome George, who lives at the Charles Darwin Research Station
on Santa Cruz
. Though it is known that tortoises once inhabited Santa Fe
, no evidence remains to tell us what that particular breed was like.
There are two basic types of Galapagos tortoise: those with shortish necks and high-domed carapaces, which come down low over both head and tail. These big beasts inhabit the lusher, thicker vegetation on the uplands of Santa Cruz
and some of the Isabela volcanoes. The second, smaller type have longer necks and legs with carapaces shaped more like Spanish-style saddles, flatter on top and rising up at the front. They are able to reach up to cactus and high foliage and come from the arid zones. A continuum exists between the the very pronounced saddleback shells, which come from the low, flat islands of Pinzon
, to the roundest dome-shaped shells from the lusher parts of Isabela
Saving tortoises threatened with extinction through captive breeding and reintroduction to the wild is a major part of the work of the Charles Darwin Research Station
on Santa Cruz
Though not an endemic to the islands, Pacific green sea turtles lay eggs and breed in the islands. At night, during the breeding season from January to June, females waddle up island beaches above the high water mark, dig holes and bury dozens of eggs. When hatched, baby turtles try to make their way to the sea, though they are vulnerable to predators such as rats, dogs, pigs and humans. If they make it safely, they disappear for years and travel huge distances. Incredibly, females are able to find their way back to the beach where they were born to lay eggs for the next generation. One of the big excitements of the Galapagos islands for snorkelers and divers is the sight of a turtle swimming nearby.
called them Imps of DarknessÖ hideous looking creatures, stupid and sluggish in their movements. But he was fascinated by these endemic reptiles, the only sea-going lizards in the world, from land iguanas who found their way to the Galapagos on rafts of vegetation. With spines like teeth running down their backs, long tails and growing to a meter [three feet
] in length, these fearsome-looking creatures seem to predate man by millions of years. Most are dirty black when wet and gray when dry, easily blending into their rocky environment.
Marine iguanas live on lava rocks on the waterís edge, dine on seaweed and can swim underwater for as long as an hour. Darwin
discovered this by throwing them into the water with weights attached to their legs, and then pulling them back up at various intervals to see which ones survived. They are common on most Galapagos islands and can often be seen in groups of similar age basking in the sun, all facing the same way, or even piled on top of each other.
In spite of their aggressive appearance, vegetarian marine iguanas wonít humans bite unless provoked. After feeding on algae, these cold-blooded creatures sun bathe on the rocks to warm their bodies and digest their food. They even bask on hotel terraces in Puerto Ayora
on Santa Cruz
. With desalination glands in their heads to filter out salt from sea water, they snort out sprays of salt through their noses like Puff the Magic Dragon.
During their mating season, which varies from island to island, males become aggressive and territorial, fighting head to head and mating with several females. Their scaly skin becomes blotchy red and green at these times, though marine iguanas on Espanola
are colorful all the year round. Females lay two to four eggs in sandy nests and defend them until they hatch but donít pay much attention to their young after that.
Thought to have the same ancestors as marine iguanas, land iguanas are now totally different in habit and habitat. At one time the Galapagos land iguana lived on almost all the islands of the archipelago, but hunting and competition with introduced animals, such as pigs, goats, dogs and rats, have confined them to Isabela
, Santa Cruz
and South Plaza
islands. This yellowish lizard, slightly bigger than its aquatic cousin, has a tough, leathery mouth, enabling it to feed on the spiky prickly pear cactus. A second species of land iguana, the Santa Fe
land iguana, is bigger and more yellow than the Galapagos land iguana and is confined to Santa Fe island
Snakes, Lizards and Geckos
Though rarely seen by visitors, two kinds of snake inhabit the archipelago: the Galapagos land snake
and the yellow-bellied sea snake
. The constricting, but inconspicuous brown or gray land snake, with yellow spots or stripes, grows to about a meter [three feet
] in length. It asphyxiates insects, lizards and hatchling but isnít dangerous to humans. The black and yellow sea snake
is rare, though its venom can be stronger than a cobraís. Harmless lava lizards
can be seen scurrying around most of the islands, as can the equally-harmless nocturnal geckos who climb vertical walls and walk upside down on ceilings hunting for insects.