Aniamals, Adaptation, and the Galapagos Islands Discover with Darwin
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Galápagos Islands
E. Lendell Cockrum Jr

Galápagos Islands, a group of generally rough volcanic islands in the Pacific Ocean some 600 miles (950 km) off the west coast of South America. They are administered by Ecuador as a territory, officially called the Archipiélago de Colón. The islands are famous for their unusual plant and animal life, which, though descended from mainland forms, evolved for countless millennia in virtual isolation from evolutionary currents on the continent. The study of these life forms by Charles Darwin, who visited the archipelago in 1835, had much to do with his development of the theory of the origin of species by natural selection.

The archipelago consists of some 16 islands and numerous islets scattered over an area of some 36,000 square miles (95,000 sq km) at or near the equator. The total land area of all of the islands, islets, and rocks probably does not exceed 3,000 square miles (8,000 sq km).

Most of the individual islands were first given English names — often more than one — by British buccaneers and whalers and later given Spanish names by Ecuadorians. In decreasing order of size, the largest islands (with their earlier English names) are Isabela (Albemarle), Santa Cruz (Indefatigable), Fernandina (Narborough), San Cristóbal (Chatham), San Salvador (James), and Santa María (Charles). Isla Isabela, the largest of the islands, covers about 1,700 square miles (4,400 sq km), or more than half of the total land area of the archipelago, and has five major volcanic peaks ranging up to 5,540 feet (1,690 meters) in height. Several of the volcanoes on this and other islands have been active in the 20th century.

The climate varies, not only from season to season but also from year to year, and considerable differences in temperature occur between the coastal areas and the higher elevations of the volcanic slopes. In general, due to the effect of the Peru (or Humboldt) Current, the climate is mild and dry, with the temperature seldom rising above 80° F (27° C) despite the islands' equatorial location.

In 1990 the population of all of the islands was estimated at less than 10,000, including temporarily resident government employees and their families. The administrative center is Baquerizo Moreno, on San Cristóbal. A limited tourist industry, utilizing an old air force landing strip and a cruise ship, offers the general public limited access to the islands.

History. The earliest recorded discovery of these islands, which were then uninhabited by humans, occurred on March 10, 1535, when a sailing ship carrying the Spaniard Fray Tomás de Berlanga, Bishop of Panamá, came within sight of the archipelago after having drifted for six days becalmed in the Peru Current. Later in the century, the mapmaker Abraham Ortelius plotted the "Isolas de Galápagos," or "Islands of the Tortoises," relying probably on Fray Tomás' description of the islands and of the giant tortoises he saw there. In the 17th century the Galápagos served as hideaways for various British buccaneers engaged in pirating Spanish ships and in looting and burning Spanish settlements on the mainland of South and Central America.

During most of the 1700s the islands remained deserted, but near the end of the century whalers and sealers began to visit the area. In 1793–1794, Capt. James Colnett of the British Royal Navy extensively explored the islands as part of an effort to set up a British whaling and sealing industry in the Pacific Ocean. American whalers also began to put in there. On the shore of a bay of Charles Island (now the Isla Santa María) the whalers set up a barrel on a post where letters from outgoing ships were deposited, to be picked up later by inbound ships. This "post office," established before 1800, still existed in 1932. Throughout much of the 19th century, the Galápagos were used by whaling ships as a rendezvous and as a source of fresh water and turtle meat.

Herman Melville, during his sojourn as a sailor on American whaling ships in 1840–1844, visited the Galápagos and later wrote of them as "Las Islas Encantadas" — the enchanted, or bewitched, islands. This name had been mentioned as early as 1684, when the British privateer Edward Davies reported that certain of his Spanish prisoners had claimed that the Galápagos were "enchanted islands…and that they were but shadows and no real islands."

Ecuador annexed the Galápagos on Feb. 12, 1832, and 60 years later renamed them the Archipiélago de Colón, in honor of Christopher Columbus. During that century a few hardy settlers established small farms at higher elevations on Santa Cruz, growing all of their own food and supplying some fresh vegetables to whaling ships.

During World War II the United States, with permission of the Ecuadorian government, operated an air base on Baltra, a small island off the north shore of Santa Cruz, from which the waters adjacent to the Panama Canal could be patrolled. An airstrip, weather station, Quonset huts, a machine shop, and a plant for distilling sea water made up the station. The base was subsequently used by a small detachment of the Ecuadorian air force. Ecuador had also maintained penal colonies in the Galápagos, but the most notorious, on Isabela, was shut down in 1958.

Ecology of the Galápagos. The islands of the archipelago all rose from the ocean floor as the tops of volcanoes, perhaps as long as 10 million years ago, and have never been connected by land to the mainland. Therefore the plants and animals must all have been introduced from elsewhere. When Europeans first visited the area, most of the islands were covered with lush vegetation, and several kinds of animals were present.

Some of the vegetation remains, its nature depending to a degree on elevation above sea level and the recentness of volcanic flows. Though many areas consist of little more than bare lava, others are covered with forests of giant cacti that rise as high as 20 feet (6 meters). Higher on some of the volcanic cones are forests of woody trees that are over 30 feet (9 meters) in height. Tree ferns and smaller plants and grasses also occur. All are descendants of mainland plants whose seeds were carried to the islands by winds, currents, or flying birds.

Land animals native to the Galápagos include a number of insects and other arthropods, land snails, lizards (notably the land iguana), snakes, a land tortoise, one kind of bat, two genera of rodents, and several birds. Many of these show no fear of humans. The birds and bats probably flew to the islands, borne by storms, while terrestrial forms were probably carried on rafts of debris that floated from the mainland. Marine animals include sea lions and marine iguanas.

As time passed, many of the plants, animals, and even shore fish changed so much in form and structure as to bear no close resemblance to their mainland ancestors. One of the most spectacular of these forms is the giant land tortoise, whose flesh was one of the chief attractions of the islands to the sailors who put in there. Uncounted thousands of these animals were carried away alive to supply fresh meat on the sailing ships, so that their numbers were reduced to the point of near extinction.

As ships sailed from the archipelago, mementos of their visits were left behind — goats, pigs, rats, mice, weed seeds, and, upon occasion, sailors. The introduction of the goats — left to multiply and serve as a source of fresh meat on later visits — succeeded too well, for they eventually destroyed much of the native vegetation on many of the islands.

The uniqueness of the animals and plants on the Galápagos has continuously fascinated biologists, most notably Charles Darwin, who, as the naturalist aboard the survey ship H. M. S. Beagle, studied these forms from Sept. 15 to Oct. 20, 1835. Having earlier made extensive observations on the South American mainland, he speculated about the relationship of the islands species to those on the continent and noted their apparent adaption to the many dissimilar habitats that existed in the various islands of the group. Thus, according to his own account, began the train of thought that led to his formulation of the evolutionary theories described in On the Origin of Species in 1859.

The early 1960s saw the launching of the Galápagos International Scientific Project, the most ambitious organized attempt to study the ecology of the archipelago. The Charles Darwin Foundation, one of a number of cosponsoring organizations, built and staffed a laboratory building on Santa Cruz.

All of the islands are now administered by the Ecuadorian National Park Service. To save the archipelago's wildlife — particularly the large tortoises — Ecuador has, by presidential decree, made game preserves of most of the islands and has listed a large number of birds, mammals, and reptiles as being strictly protected.

   
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