''Chelonoidis niger guentheri'', commonly known as the Sierra Negra giant tortoise or Günther's giant tortoise, is a
subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
of
Galápagos tortoise
The Galápagos tortoise or Galápagos giant tortoise (''Chelonoidis niger'') is a species of very large tortoise in the genus ''Chelonoidis'' (which also contains three smaller species from mainland South America). It comprises 15 subspecies (13 ...
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
. The
specific epithet
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
''guentheri'' honours zoologist
Albert Günther
Albert Karl Ludwig Gotthilf Günther FRS, also Albert Charles Lewis Gotthilf Günther (3 October 1830 – 1 February 1914), was a German-born British zoologist, ichthyologist, and herpetologist. Günther is ranked the second-most productive re ...
.
Taxonomy
This tortoise is a subspecies of ''Chelonoidis niger'', and is sometimes considered a distinct species.
Description
Male tortoises grow to about 120 cm and females to about 92 cm in length and may have either domed or flattened
carapace
A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
s.
Behaviour
Feeding
The tortoises graze on shrubs and low-growing herbaceous vegetation, consuming herbs, grass,
cacti
A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...
,
lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.
Breeding
Male tortoises compete with each other by extending their necks, gaping, biting and shell-bumping. They produce loud guttural noises while mating. Females lay clutches of usually 6–11 (occasionally up to 17) eggs. Juvenile tortoises tend to remain in the warmer, lowland, part of the subspecies' range for the first 10–15 years of their lives.
Distribution and habitat
The tortoise's range is limited to an area of about 800 km2 on the slopes of the
Sierra Negra
Sierra Negra (also, and perhaps more properly, Cerro La Negra) is an extinct volcano located in the Mexican state of Puebla, close to the border with Veracruz. At officially above sea level, it is the fifth-highest peak in Mexico. Sierra Neg ...
volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates are ...
, from near sea-level to an altitude of around 1,000 m, at the southern end of Isabela Island. There it inhabits deciduous and evergreen forests, dry
grassland
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
, introduced vegetation and agricultural land. The population is estimated to comprise some 400–700 mature individuals, a decline of 99% from an estimated 71,000 individuals prior to human contact with the islands.
Conservation
The subspecies is considered to be Critically Endangered. The population was historically overexploited for food and oil by sailors and settlers, and some poaching continues. Other threats include predation of eggs and hatchlings, as well as habitat degradation, by introduced animals, including dogs,
rodent
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...
s, pigs, goats and fire ants. Volcanic eruptions also threaten the tortoises and their habitat.