Galapagos Land Iguana
Encyclopedia
The Galapagos Land Iguana (Conolophus subcristatus) is a species of lizard
in the Iguanidae
family. It is one of three species of the genus Conolophus
. It is endemic to the Galápagos Islands
, primarily the islands of Fernandina
, Isabela
, Santa Cruz
, North Seymour
, Hood
and South Plaza
.
and coloration among different island populations. There are two taxonomically distinct forms of Conolophus inhabiting the western part of the islands (C. rosada and C. pallidus
) and one in the central part (C. subcristatus). Its generic name
, Conolophus, is derived from two Greek
words: conos (κώνος) meaning "spiny" and lophos (λοφος) meaning "crest" or "plume", denoting the spiny crests along their backs. Its specific name subcristatus is derived from the Latin
words sub meaning "lesser" and cristatus meaning "crested," and refers to the low crest of spines along the animal's back which is not as tall as in most iguanids.
described the Galapagos Land Iguana as "ugly animals, of a yellowish orange beneath, and of a brownish-red colour above: from their low facial angle they have a singularly stupid appearance." The Galapagos Land Iguana grows to a length of three to five feet with a body weight of up to twenty-five pounds, depending upon which island they are from. Being cold-blooded
, they absorb heat from the sun by basking on volcanic rock
, and at night sleep in burrow
s to conserve their body heat. These iguanas also enjoy a symbiotic
relationship with birds; the birds remove parasites
and tick
s, providing relief to the iguanas and food for the birds.
s supplementing their diet with insects, centipede
s and carrion
. Because fresh water is scarce on the islands it inhabits, the Galapagos Land Iguana obtains the majority of its moisture from the prickly-pear cactus
that makes up 80% of its diet: fruit, flowers, pads, and even spines. During the rainy season it will drink from available standing pools of water and feast on yellow flowers of the genus Portulaca
.
It is estimated that the Galapagos Land Iguana has a 50 to 60-year lifespan.
Galapagos Land Iguanas become sexually mature anywhere between eight and fifteen years of age, depending on which island they are from. Mating season also varies between islands, but soon after mating, the females migrate to sandy areas to nest, laying 2-25 eggs in a burrow 18 inches deep. The eggs hatch anywhere from 90 to 125 days later.
On South Plaza Island
, where the territories of Marine Iguana
s and Land Iguanas overlap, the two sometimes interbreed, resulting in a mixture of features from each species; resulting in what is known as a Hybrid Iguana
. The most likely unions tend to be between male Marine Iguanas and Female Land Iguanas. Despite their long separation time and their being two distinct species from different genera, the offspring are viable, although likely sterile.
at one time that naturalist Charles Darwin remarked when it was called King James Island that "...when we were left at James, we could not for some time find a spot free from their burrows on which to pitch our single tent". In the years since then, entire populations (including all the animals on Santiago Island) have been wiped out by introduced feral animals such as pigs, rats, cats, and dogs.
It has been suggested that a pink morph of the Galapagos population is actually a genetically distinct subpopulation. This would warrant a separate species designation for the pink subpopulation. Subsequent genetic analysis of the pink morphs have suggested that the subpopulation split off from the main C. subcristatus one at least five million years ago.
. These animals became extinct on Baltra by 1954, allegedly wiped out by soldiers stationed there who shot the iguanas for amusement. However, in the early 1930s, William Randolph Hearst
had translocated a population of Land Iguanas from Baltra to North Seymour Island
, a smaller island just a few hundred metres north of Baltra because he could not understand why no iguanas were present there. Hearst's translocated iguanas survived, and became the breeding stock for the Charles Darwin Research Station
captive breeding program which has successfully reintroduced the species to Baltra and a number of other areas. Visitors today frequently see iguanas on both the runway of the Baltra airport or while they cross the road.
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
in the Iguanidae
Iguanidae
Iguanidae is a family of lizards, composed of iguanas and related species.-Classification of Iguanidae:Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. .Frost et...
family. It is one of three species of the genus Conolophus
Conolophus
The Galápagos land iguanas comprise the genus Conolophus of the Galápagos Islands. The name Conolophus is derived from two Greek words: conos meaning "spiny" and lophos meaning "crest" or "plume", denoting the spiny crests along the backs of these species...
. It is endemic to the Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
, primarily the islands of Fernandina
Fernandina Island
Fernandina Island is the third largest, and youngest, island of the Galápagos Islands. Like the others, the island was formed by the Galápagos hotspot...
, Isabela
Isabela Island (Ecuador)
Isabela Island is the largest island of the Galápagos with an area of , and length of nearly 4 times larger than Santa Cruz, the next largest of the islands. This island was named in honor of Queen Isabella of Spain, who sponsored the voyage of Columbus. . By the English, it was named Albemarle...
, Santa Cruz
Santa Cruz Island (Galápagos)
Santa Cruz Island is one of the Galápagos Islands with an area of and a maximum altitude of .Situated in the center of the archipelago, Santa Cruz is the second largest island after Isabela. Its capital is Puerto Ayora, the most populated urban centre in the islands. On Santa Cruz there are some...
, North Seymour
North Seymour Island
North Seymour is a small island near to Baltra Island in the Galapagos Islands. It was formed by uplift of a submarine lava formation. The whole island is covered with low, bushy vegetation....
, Hood
Española Island
Española Island is part of the Galápagos Islands. The English named it Hood Island after Viscount Samuel Hood. It is located in the extreme southeast of the archipelago and is considered, along with Santa Fe, one of the oldest, at approximately four million years...
and South Plaza
South Plaza Island
South Plaza is a small island off the east coast of Santa Cruz in the Galapagos Islands. It has an area of 0.13 km˛ and a maximum altitude of 23 meters....
.
Taxonomy
The Galapagos Land Iguana varies in morphologyMorphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and coloration among different island populations. There are two taxonomically distinct forms of Conolophus inhabiting the western part of the islands (C. rosada and C. pallidus
Barrington Land Iguana
The Barrington Land Iguana, or the Santa Fe Land Iguana, is a species of lizard in the Iguanidae family. It is one of three species of Conolophus.It is endemic to Santa Fe Island in the Galapagos.-Taxonomy:...
) and one in the central part (C. subcristatus). Its generic name
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
, Conolophus, is derived from two Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
words: conos (κώνος) meaning "spiny" and lophos (λοφος) meaning "crest" or "plume", denoting the spiny crests along their backs. Its specific name subcristatus is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
words sub meaning "lesser" and cristatus meaning "crested," and refers to the low crest of spines along the animal's back which is not as tall as in most iguanids.
Anatomy and morphology
Charles DarwinCharles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
described the Galapagos Land Iguana as "ugly animals, of a yellowish orange beneath, and of a brownish-red colour above: from their low facial angle they have a singularly stupid appearance." The Galapagos Land Iguana grows to a length of three to five feet with a body weight of up to twenty-five pounds, depending upon which island they are from. Being cold-blooded
Ectotherm
An ectotherm, from the Greek εκτός "outside" and θερμός "hot", refers to organisms that control body temperature through external means. As a result, organisms are dependent on environmental heat sources and have relatively low metabolic rates. For example, many reptiles regulate their body...
, they absorb heat from the sun by basking on volcanic rock
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...
, and at night sleep in burrow
Burrow
A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...
s to conserve their body heat. These iguanas also enjoy a symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
relationship with birds; the birds remove parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
and tick
Tick
Ticks are small arachnids in the order Ixodida, along with mites, constitute the subclass Acarina. Ticks are ectoparasites , living by hematophagy on the blood of mammals, birds, and sometimes reptiles and amphibians...
s, providing relief to the iguanas and food for the birds.
Diet and longevity
Land iguanas are primarily herbivorous; however, some individuals have shown that they are opportunistic carnivoreCarnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
s supplementing their diet with insects, centipede
Centipede
Centipedes are arthropods belonging to the class Chilopoda of the subphylum Myriapoda. They are elongated metameric animals with one pair of legs per body segment. Despite the name, centipedes can have a varying number of legs from under 20 to over 300. Centipedes have an odd number of pairs of...
s and carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. Because fresh water is scarce on the islands it inhabits, the Galapagos Land Iguana obtains the majority of its moisture from the prickly-pear cactus
Opuntia
Opuntia, also known as nopales or paddle cactus , is a genus in the cactus family, Cactaceae.Currently, only prickly pears are included in this genus of about 200 species distributed throughout most of the Americas. Chollas are now separated into the genus Cylindropuntia, which some still consider...
that makes up 80% of its diet: fruit, flowers, pads, and even spines. During the rainy season it will drink from available standing pools of water and feast on yellow flowers of the genus Portulaca
Portulaca
Portulaca is the type genus of the flowering plant family Portulacaceae, comprising about 40-100 species found in the tropics and warm temperate regions. They are also sometimes known as Rose Moss or more commonly Moss Roses....
.
It is estimated that the Galapagos Land Iguana has a 50 to 60-year lifespan.
Reproduction
On South Plaza Island
South Plaza Island
South Plaza is a small island off the east coast of Santa Cruz in the Galapagos Islands. It has an area of 0.13 km˛ and a maximum altitude of 23 meters....
, where the territories of Marine Iguana
Marine iguana
The Marine Iguana is an iguana found only on the Galápagos Islands that has the ability, unique among modern lizards, to live and forage in the sea, making it a marine reptile. The Iguana can dive over 30 ft into the water. It has spread to all the islands in the archipelago, and is...
s and Land Iguanas overlap, the two sometimes interbreed, resulting in a mixture of features from each species; resulting in what is known as a Hybrid Iguana
Hybrid Iguana
The Hybrid Iguana is a first generation hybrid, the result of intergeneric breeding between a male Marine Iguana and a female Land Iguana on South Plaza Island in the Galápagos Islands where the territories of the two species overlap.- Anatomy and morphology:Marine Iguanas have sharp claws and...
. The most likely unions tend to be between male Marine Iguanas and Female Land Iguanas. Despite their long separation time and their being two distinct species from different genera, the offspring are viable, although likely sterile.
Population
It is estimated that between 5,000 and 10,000 land iguanas are found in the Galapagos. These iguanas were so abundant on Santiago IslandSantiago Island (Galápagos)
Santiago Island is an island of the Galápagos Islands. It is also known as San Salvador, named after the first island discovered by Columbus in the Caribbean Sea , or as James Island. The island, which consists of two overlapping volcanoes, has an area of 585 km² and a maximum altitude of...
at one time that naturalist Charles Darwin remarked when it was called King James Island that "...when we were left at James, we could not for some time find a spot free from their burrows on which to pitch our single tent". In the years since then, entire populations (including all the animals on Santiago Island) have been wiped out by introduced feral animals such as pigs, rats, cats, and dogs.
It has been suggested that a pink morph of the Galapagos population is actually a genetically distinct subpopulation. This would warrant a separate species designation for the pink subpopulation. Subsequent genetic analysis of the pink morphs have suggested that the subpopulation split off from the main C. subcristatus one at least five million years ago.
Recovery efforts
Beginning in the early 1990s the Galapagos Land Iguana is the subject of an active re-introduction campaign on Baltra IslandBaltra Island
Baltra Island, or Isla Baltra, is a small island of the Galápagos Islands. Also known as South Seymour , Baltra is a small flat island located near the center of the Galápagos. It was created by geological uplift...
. These animals became extinct on Baltra by 1954, allegedly wiped out by soldiers stationed there who shot the iguanas for amusement. However, in the early 1930s, William Randolph Hearst
William Randolph Hearst
William Randolph Hearst was an American business magnate and leading newspaper publisher. Hearst entered the publishing business in 1887, after taking control of The San Francisco Examiner from his father...
had translocated a population of Land Iguanas from Baltra to North Seymour Island
North Seymour Island
North Seymour is a small island near to Baltra Island in the Galapagos Islands. It was formed by uplift of a submarine lava formation. The whole island is covered with low, bushy vegetation....
, a smaller island just a few hundred metres north of Baltra because he could not understand why no iguanas were present there. Hearst's translocated iguanas survived, and became the breeding stock for the Charles Darwin Research Station
Charles Darwin Research Station
The Charles Darwin Research Station is a biological research station operated by the Charles Darwin Foundation. It is located in Puerto Ayora on Santa Cruz Island in the Galapagos Islands, with satellite offices on Isabela and San Cristóbal islands.- Background :In Puerto Ayora, Santa Cruz Island,...
captive breeding program which has successfully reintroduced the species to Baltra and a number of other areas. Visitors today frequently see iguanas on both the runway of the Baltra airport or while they cross the road.