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The Galapagos Islands
By Cindy Grigg
The Galapagos Islands (Guh LAH puh goess) are a group of thirteen islands lying
six hundred miles west off the coast of Ecuador. They were first called the
"Enchanted Islands" by early Spanish explorers. The land mass is approximately
three thousand square miles. They are one of the most active volcanic sites in the
world. In 1892 the Enchanted Islands were renamed Archipiélago de Colón or Islas
Galápagos by Ecuador which had annexed the islands in 1832. Either name or both
may appear on a map. But most people still call them Galapagos, the Spanish word
describing the tortoises that live on the islands.
The Galapagos Islands are most famous for being the object of Charles Darwin's
study of their unique plants and wildlife. In 1835, the young Charles Darwin came to
the islands on the HMS Beagle. The Beagle visited the islands for five weeks.
Darwin visited at least four of the islands. He collected and classified plant and
animal specimens. Darwin wrote about the giant tortoises the islands were named for
and the differences he saw among them. Darwin wondered what could account for
such an odd assortment of creatures in the Galapagos and the subtle and sometimes
stark differences in some species. He puzzled over these questions, and his
observations and notes led to the formation of the theory of evolution by natural selection. He published his
theory and comments about these strange islands in 1859 in his book On the Origin of Species. In the almost one
hundred fifty years since the publication of his book, his ideas about evolution have become the central theory of
biology.
Each major island boasts its own unique ecosystem and geographic features. At least nine hundred plant
species have been identified here, and two hundred of these grow only in the Galapagos. Darwin wondered about
the cormorant birds he saw there. In South America cormorants fly. But in the Galapagos, they have stubby
wings that make flight impossible, and they have extremely long necks. He theorized that because living things
do not generally create exact duplicates of themselves, those changes or mutations can help or hinder them,
depending on their environment.
The isolation of the Galapagos Islands, plus the hardship of living there, meant this: to survive, a plant or
animal species had to adapt to the conditions or die out. This reasoning could account for cormorants that no
longer needed strong wings to fly considerable distances for food. Instead they would have developed long necks
to fish in the waters around the islands. The different varieties of tortoises evolved in response to where they
lived. Just as the cormorants developed long necks and stubby wings on islands where water and vegetation were
scarce, tortoises developed long necks and saddlebacks to reach taller plants more easily.
On islands having more than one species of tortoise, researchers believe that small, distinct ecosystems were
responsible for the differences. Because there were no large predators and because man did not arrive until the
sixteenth century, species that may have been doomed elsewhere could thrive in the Galapagos. Many of the
seemingly strange animals, the marine iguana, for example, may have been spread over a greater area but
survived only in the Galapagos. The only land mammals are rice rats and two species of bats.
Endemic species are found only in one place; they are unique to that area. The islands contain some
fifty-five native birds, twenty-seven of which are found only in the Galapagos, and some of these are found only
on one of the islands. Ancestors of the small Galapagos penguins probably migrated from further south. These
are the only penguins that live in tropical waters. The thirteen species of finches, known as Darwin's finches,
have beaks adapted to different varieties of food. Darwin noticed that each species was well suited to the food it
ate. Finches that ate insects had sharp, needlelike beaks. Finches that ate seeds had strong, wide beaks. Plants,
too, have evolved into unique species. One species of prickly pear cactus has grown into a "tree" with a diameter
of about four feet and may be as tall as forty feet!
Darwin wrote in his diary "by far the most remarkable feature of this archipelago is that the different islands,
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to a considerable extent, are inhabited by a different set of beings." These islands have been a popular location for
scientific study for nearly one hundred fifty years. Their geographic isolation from the mainland, varied habitats,
recent volcanic origin, and variety of endemic species help scientists study how plants and animals change over
time.
The Galapagos Islands
Questions
1. Where are the Galapagos Islands located?
2. The Galapagos are most famous for:
A. their giant tortoises
B. their location near the equator
C. Darwin's study of their unique plants and wildlife
D. their variety of mammals
3. What did early Spanish explorers call the islands?
A. the Enchanted Islands
B. the Weird Islands
C. the Falkland Islands
D. the Sandwich Islands
4. Unique species that are found in only one place are called:
A. epidemic species
B. pandemic species
C. indemnity species
D. endemic species
5. How far away from the South American continent are the Islands?
A. six thousand miles
B. six miles
C. sixty miles
D. six hundred miles
Darwin visited the Galapagos in 1835, but he didn't publish his ideas until 1859. Explain why you think Darwin
waited so long to publish.
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Hypothesize why there are almost no mammals on the Galapagos Islands. Use details from the story to support
your hypothesis.