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Chinchillas
The Scientific Breakdown

Article compiled by - Anjela Ross
For the Chinchilla Club

This indepth article that I came across online, breaks down the whole of the classes that a Chinchilla can be included into. Now you have absolutely no excuse for not knowing exactly what a Chinchilla is and where it fits in, into the larger picture. This is your chance to read up and say for sure that you know exactly what a Chinchilla is!

Classification


Kingdom - Animalia
Phylum - Chordata
Class - Mammalia
Order - Rodentia
Suborder - Hystricognathi
Family - Chinchillidae
Genus - Chinchilla
Species - Chinchilla Lanigera


What does it all mean????

KINGDOM  -  ANIMALIA

All animals are members of the Kingdom Animalia, also called Metazoa. This Kingdom does not contain the prokaryotes (Kingdom Monera, includes bacteria, blue-green algae) or the protists (Kingdom Protista, includes unicellular eukaryotic organisms). All members of the Animalia are multicellular, and all are heterotrophs (that is, they rely directly or indirectly on other organisms for their nourishment). Most ingest food and digest it in an internal cavity.

Animal cells lack the rigid cell walls that characterize plant cells. The bodies of most animals (all except sponges) are made up of cells organized into tissues, each tissue specialized to some degree to perform specific functions. In most, tissues are organized into even more specialized organs. Most animals are capable of complex and relatively rapid movement compared to plants and other organisms. Most reproduce sexually, by means of differentiated eggs and sperm. Most animals are diploid, meaning that the cells of adults contain two copies of the genetic material. The development of most animals is characterized by distinctive stages, including a zygote, formed by the product of the first few division of cells following fertilization; a blastula, which is a hollow ball of cells formed by the developing zygote; and a gastrula, which is formed when the blastula folds in on itself to form a double-walled structure with an opening to the outside, the blastopore.

Somewhere around 9 or 10 million species of animals inhabit the earth; the exact number is not known and even our estimates are very rough. Animals range in size from no more than a few cells to organisms weighing many tons, such as blue whales and giant squid. Most animals inhabit the seas, with fewer in fresh water and even fewer on land.

Research continues on the evolutionary relationships of the major groups of animals. For the sake of convenience, we shall follow the system outlined in Hickman and Roberts (1994), but for some groups we shall incorporate the results of current research in our classification and discussion.

PHYLUM  -  CHORDATA

Chordates are defined as organisms that possess a structure called a notochord, at least during some part  of their development. The notochord is a rod that extends most of the length of the body when it is fully  developed. Lying dorsal to the gut but ventral tothe central nervous system, it stiffens the body and acts as support during locomotion. Other characteristics shared by chordates include the following (from Hickman and Roberts, 1994):
  1. bilateral symmetry
  2. segmented body, including segmented muscles
  3. three germ layers and a well-developed coelom.
  4. single, dorsal, hollow nerve cord, usually with an enlarged anterior end (brain)
  5. tail projecting beyond (posterior to) the anus at some stage of development
  6. pharyngeal pouches present at some stage of development
  7. ventral heart, with dorsal and ventral blood vessels and a closed blood system
  8. complete digestive system
  9. bony or cartilaginous endoskeleton usually present.



CLASS  -  MAMMALIA


All mammals share three characteristics not found in other animals: 3 middle ear bones; hair; and the production of milk by modified sweat glands called mammary glands.

Mammals hear sounds after they are transmitted from the outside world to their inner ears by a chain of three bones, the malleus, incus, and stapes . Two of these, the malleus and incus, are derived from bones involved in jaw articulation in most other vertebrates.

Mammals have hair. Adults of some species lose most of their hair, but hair is present at least during some phase of the ontogeny of all species. Mammalian hair, made of a protein called keratin, serves at least four functions. First, it slows the exchange of heat with the environment (insulation). Second, specialized hairs (whiskers or "vibrissae") have a sensory function, letting the owner know when it is in contact with an object in its external environment. These hairs are often richly innervated and well-supplied with muscles that control their position. Third, through their color and pattern, hairs affect the appearance of a mammal. They may serve to camouflage, to announce the presence of especially good defense systems (for example, the conspicuous color pattern of a skunk is a warning to predators), or to communicate social information (for example, threats, such as the erect hair on the back of a wolf; sex, such as the different colors of male and female capuchin monkeys; presence of danger, such as the white underside of the tail of a whitetailed deer). Fourth, hair provides some protection, either simply by providing an additional protective layer (against abrasion or sunburn, for example) or by taking on the form of dangerous spines that deter predators (porcupines, spiny rats, others).

Mammals feed their newborn young with milk, a substance rich in fats and protein that is produced by modified sweat glands called mammary glands. These glands, which take a variety of shapes, are usually located on the ventral surface of females along paths that run from the chest region to the groin. They vary in number from two (one right, one left, as in humans) to a dozen or more.

Other characteristics found in most mammals include highly differentiated teeth; teeth are replaced just once during an individual's life (this condition is called diphyodonty, and the first set is called "milk teeth); a lower jaw made up of a single bone, the dentary; four-chambered hearts, a secondary palate separating air and food passages in the mouth; a muscular diaphragm separating thoracic and abdominal cavities; highly developed brain; endothermy and homeothermy; separate sexes with the sex of an embryo being determined by the presence of a Y or 2 X chromosomes; and internal fertilization.

The Class Mammalia includes around 5000 species placed in 26 orders (systematists do not yet agree on the exact number or on how some orders are related to others). Mammals can be found in all continents and seas. In part because of their high metabolic rates (associated with homeothermy and endothermy), they often play an ecological role that seems disproportionately large compared to their numerical abundance.


Order - Rodentia ( Rodents )

With over 2000 living species placed in about 30 families, rodents are by far the largest order of mammals, at least in terms of number of taxa (well over 40% of mammalian species belong to the order Rodentia!). Rodents range in size from pygmy mice weighing 5 gms to capybaras, the largest of which weigh over 70 kg. They are found around the world except in Antarctica, New Zealand, and on some oceanic islands. Ecologically, they are incredibly diverse. Some species spend their entire lives above the ground in the canopy of rainforests; others seldom emerge from beneath the ground. Some species are highly aquatic, while others are equally specialized for life in deserts. Many are to some degree omnivorous; others are highly specialized, eating, for example, only a few species of invertebrates or fungi.

Despite their morphological and ecological diversity, all rodents share one characteristic: their dentition is highly specialized for gnawing. All rodents have a single pair of upper and a single pair of lower incisors, followed by a gap (diastema), followed by one or more molars or premolars. No rodent has more than one incisor in each quadrant, and no rodent has canines. Rodent incisors are rootless, growing continuously. Their anterior and lateral surfaces are covered with enamel, but their posterior surface is not. During gnawing, as the incisors grind against each other, they wear away the softer dentine , leaving the enamel edge as the blade of a chisel. This "self sharpening" system is very effective and is one of the keys to the enormous success of rodents.

The condition of a dominant pair of incisors used for gnawing, followed by a long diastema, is not unique to rodents, and in fact rodents are relative latecomers to this condition (even though as a group, they have a very old fossil history, going back to Paleocene times). It is even seen in a group of therapsids (ancestors of mammals), the tritylodonts, which lived during the Jurassic. Multituberculates, a very large and successful but now extinct group of early mammals, had a similar pattern. So do wombats, hyraxes, aye-ayes , and lagomorphs, to give a few examples chosen from modern mammals. Rodents have specialized in gnawing to an extreme, however, seen in few or no other groups of vertebrates.

The main muscle used in chewing by rodents is the masseter, and the rodents can be divided into several groups based on exactly how they use these muscles. These groupings have been used in several ways in the past to classify rodents.

Other characteristics of rodents include a well-developed pterygoid region of the skull (the pterygoid muscles, which originate in this region, participate in the movement of the lower jaw), an elongate glenoid fossa with no postglenoid process (permitting the lower jaw to move forwards and backwards), complete zygomatic arch with the midportion spanned by the jugal, large paroccipital processes, alisphenoid canal present (but sometimes short and hard to see), and region between the orbits sometimes constricted and sometimes with postorbital processes. Other characteristics include clavicles usually present, the feet primitively 5-toed (the pollex often very small), digits 2-5 with claws, pollex and hallux sometimes with a nail, reduced temporalis muscle, and many others.


Family - Chinchillidae

(Chinchillas and viscachas)

Six species in 3 genera make up this family, which is found along the central and southern Andes and throughout most of Patagonia in southern South America.

Members of this family are medium (500 gms) to large-sized rodents (8kg) with thick, soft fur; well-developed hind limbs, which are longer than the forelimbs; large eyes; and moderately large ears. Their tails are bushy and range from short up to about 1/3 the length of the body; in the species with the longest tail (Lagostomus), however, the tail is easily broken and often partly lost. Fleshy pads called pallipes are found on the feet of all chinchillids. The soles are not furry. The forefeet have four toes, which are easily manueverable and used for grasping. The number of toes on the hind feet is reduced to 4 in Lagidium and Chinchilla (both of which have weakly developed hind claws) and 3 in Lagostomus (strong hind claws), which are powerful diggers. Plains viscachas (Lagostomus) have a striking black and white facial pattern, lacking in the other species; the bodies of all are grey or grey-brown dorsally and paler on the venters.

The crania of chinchillids are hystricognathous, but the condition is not as strongly developed in this group as in most of the South American Hystricognathi, probably due to secondary loss. They are, however, strongly hystricomorphous, with a much-enlarged infraorbital foramen and reduced zygomatic plate. The mandibles have no masseteric crest. Lacrimals are large, and the lacrimal canal opens on the side of the rostrum. The auditory bullae range from moderately large to extremely inflated (chinchillas), and the paroccipital processes can be either long or short. The cheek teeth of chinchillids (dental formula 1/1, 0/0, 1/1, 3/3 = 20) are hypsodont and evergrowing (rootless). Their occlusal surfaces are composed of 2 or 3 closely packed lamellar plates. All chinchillids have fairly delicate incisors.

Members of this family often jump bipedally, but mostly they move on all four limbs. Chinchillas and mountain viscachas (Lagidium) live in mountainous, rocky areas, where they move over and through the rocks with great agility. They are not strong diggers. Plains viscachas live in the great plains areas of Argentina, from the Chaco in the north to Patagonia in the south. They are excellent diggers and construct extensive burrow systems. This habit that has not endeared them to ranchers, whose livestock sometimes break legs when they step into viscacha holes.

Chinchillas, mountain viscachas, and plains viscachas are all colonial, living in groups that range from a few individuals to hundreds. Mountain and especially plains viscachas have fairly large repertoires of vocalizations used in social interactions. Unfortunately, chinchillas are nearly extinct in the wild, so little is known of their behavior under natural conditions. Viscachas, once abundant, are now seriously threatened and uncommon. Mountain viscachas are uncommon and live in remote areas. As a result, none of the species in this family have been thoroughly studied under natural conditions. All are primarily vegetarian. It is said that 10 plains viscachas eat as much as one sheep, another aspect of their biology that has earned them the wrath of agriculturalists.

Reference written by Colette Hendricks - University of Michigan
Taken from -  

The Animal Diversity Web - which is intended as an educational resource written largely by and for college students. It doesn't contain all the latest scientific information about every species.

Geographic Range

Neotropical: Chinchilla lanigera is currently restricted to the mountains of northern Chile 

Physical characteristics

Chinchilla lanigera` has a head and body length equal to 225-380 mm, and a tail averaging 75-150 mm. The species is sexually dimorphic with the female weighing up to 800 g and the male only 500 g.

The fur of members of this species is extremely dense and soft. Each hair usually has a black tip, and as many as 60 hairs grow out of one follicle. The ventral side is usually bluish, pearl, or brownish gray, and the belly is yellowish-white. Its tail is furry with coarse hairs on the dorsal surface.

The head is broad and the external ears are large. Chinchillas have large, black eyes with a vertical split pupil, vestigial cheek pouches, and incisors with colored enamel . Both the forefoot and hindfoot have four digits with stiff bristles
surrounding the weak claws.

Natural History

Food Habits

The long-tailed chinchilla is omnivorous. It feeds on many types of vegatation, but primarily on grass and seeds. They also eat insects and bird eggs. While eating, C. lanigera sits erect and holds the food in its forepaws.

Domesticated chinchillas are fed alfalfa, hay, wheat, corn, oats, and commercial food pellets.

Behaviour

Chinchilla lanigera is found in the barren, arid areas of mountains at elevations of 3,000-5,000 meters. These animals den in crevices and holes among the rocks.

Biomes: mountains

Economic Importance for Humans

Positive

Chinchillas have been hunted for human apparel since the early 1900s. Around 1900, an estimated 500,000 chinchilla skins were exported annually from Chile. Chinchilla pelt is considered by some to be the most valuable pelt in the world, and coats have sold as much as $100,000.

Conservation

Status:

  • IUCN: Vulnerable
  • CITES: Appendix I

IUCN lists Chinchilla lanigera as vulnerable. Chinchillas are now protected by law in their natural habitat, yet hunting of this animal for its fur continues in remote areas, which makes enforcement hard. Populations of C. lanigera have also dwindled because of burning and harvesting of the algarobilla shrub in the lower altitudes. Fewer than 10,000 C. lanigera are thought to have survived in the wild, and attempts to reintroduce chinchillas into the wild have failed. Today, hundreds of chinchillas are bred commercially.

Other Comments

The long-tailed chinchilla has been harvested since pre-Columbian times by the Incas and Native Americans of Chile. Chinchilla lanigera was plentiful at this time, and one author reported that one could see an many as 1000 animals in one day. Chinchillas were first bred in captivity at the end of the 19th century, but it was not until 1920 that commercial breeding began. Domesticated chinchillas have been described as smarter than the average rabbit and more fun than rats. They memorize trails and have good memories. Chinchillas are very shy animals and are very trusting of their owners.

Chinchilla lanigera is also referred to as Chilean chinchilla.




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