Science Fair Project Encyclopedia
Cavia magna Guinea pigs (also called cavies) are rodents belonging to the family Caviidae and the genus Cavia. Though guinea pigs are currently classified in order Rodentia, there was historically some scientific dispute over whether or not they are actually rodents, as recent evidence from mitochondrial DNA was thought to indicate that the Hystricognathi may belong to a different evolutionary offshoot, and therefore a different order.
Despite their common name, the animals are not pigs, nor do they come from Guinea. Although there are more than 20 different species, the one most familiar to people is C. porcellus, the common guinea pig. The majority of information in this article is about the common guinea pig.
The common guinea pig was first domesticated c. 2000 BC for food in the Andean region of South America, in what is now Peru. They continue to be a food source in the region, subsisting off a family's vegetable scraps as a half pet/half future meal. Guinea pigs are called cuy (pl. cuyes) in Perú and considered a culinary delicacy, prepared usually by roasting; the general opinion considers them similar to rabbit in taste. They also play the role of evil-spirit collector in traditional healing rituals.
Dutch and English traders brought guinea pigs to Europe, where they quickly became popular as exotic pets. How they came to be thought of as "pigs" is not clear, it is thought that some of the sounds they make reminded people of pigs. They are also built something like a pig: a large head relative to the body, a stout neck, and a rounded rump with no tail of any consequence. Whatever the reason, this perception of pigginess occured in many languages other than English; the German word for them is Meerschweinchen, literally "Little Sea Pigs" (this is believed to be because they come from overseas and supposedly taste a bit like pork), the Russian word for them is morskaja svinka (Sea Pig; Морская свинка), the French word is Cochon d'Inde, (Indian pig) the Dutch used to call it guinees biggetje (Guinean piglet), in Sweden they are called marsvin (a combination of the Latin word mare for ocean, and Swedish svin which means pig) and in Greek they are called 'indika xoiridia' (Small Indian Pigs ; ινδικά χοιρίδια).
The origin of "guinea" in the title guinea pig is even harder to explain. One theory is that the animals were brought to Europe by way of Guinea and people came to think they had come from there. Another theory is they were sold as the closest thing to a pig you could get for a guinea, an old British coin with a value of 21 shillings (1.05 GBP in the modern decimal currency). Since the Dutch name refers to Guinea rather than to the British coin and the fact that the first guinea pig was described in 1554 by the Swiss naturalist Konrad Gesner (more than a hundred years before the first guinea was struck), the former theory is more likely.
Traits and Environment
Guinea pigs are large for rodents, weighing between 1 and 3 pounds (0.5 and 1.5 kg) and measuring 10 to 15 inches (250 to 400 mm) long. They live an average of five years with a maximum age of about eight years. They are social, living in the wild in small groups which consist of sows (females), a boar (male), and the young (which in a break with the preceding porcine nomenclature are called pups).
In their wild state, Guinea pigs are found on grassy plains and occupy an ecological niche similar to that of the cow. They move together in small groups (herds) eating grass or whatever other plants they come across. They are crepuscular, tending to be most active during dawn and dusk, when it is harder for predators to spot them. If startled they can run for cover with surprising speed. Domesticated guinea pigs however, have longer periods of activity, followed by short periods of sleep in between, scattered randomly over the 24 hours of the day.
Unlike many rodents such as mice, rats, or squirrels, guinea pigs are not very athletic. Jumping, climbing, and fearlessness in the face of heights were not skills guinea pigs needed in the environment in which they evolved, although they can hop over small obstacles with agility.
Guinea pigs are vocal animals, with a fairly large vocabluary. Some sounds are:
- The "Wheek". A loud noise that sounds about the same as it's written form. Means "feed me" or "pay attention", or possibly "I'm hurt".
- "Rumbling". This sound is related to guinea pig dominance. It is a purring sound, made in the throat.
- "Clicking". This sound is sometimes made by clacking the teeth together, and means "I'm annoyed", or "go away."
- "Chattering". A similar sound to the one above, this sound shows anger.
- "Purring". This sound means that the guinea pigs are content. Similar to cats.
The gestation lasts from 68 to 72 days, which is quite long for such a small animal. As a consequence pups are already well developed (including fur, teeth, claws and full eyesight) when they are born. The young are mobile from birth, and depending on the environment, will usually venture outdoors within a week. Pups begin eating solid food after a couple of days, though continue to suckle also. Males may demonstrate courtship behavior (following young females and making a "warbling" sound) in the second or third week after birth. Females can breed when only three weeks old. Litters vary from 2 or 3 young to as many as 8 or more. In smaller litters, difficulties may occur during labour, due to oversized pups. Up to half the young may be lost in larger litters, as the mother cannot attend to the newborns fast enough. If a large number survive, it is likely that the weakest (or runts of the litter), will be insufficiently nursed, resulting occasionally in the death of one or two pups.
Domestic Guinea Pigs
Domesticated guinea pigs come in many varieties which have been developed since their arrival in Europe and North America. These varieties vary widely in hair and color composition. The most common varieties found in pet stores are the English Short Hair which has a smooth, glossy, short coat, and the Abyssinian which has a rough coat made of cowlicks, crests, and swirls called rosettes. Each of these varieties come in a number of colors and color patterns. The rarer Peruvian has very long hair, hanging all the way to the ground.
Guinea pigs are widely considered to be good pets. They are generally easy to care for, and while they do require frequent cage cleaning and companionship, with a little diligence all their needs can easily be met. They are considered by many to be very cute and are very verbal (they squeak) in contact with humans. Guinea pigs who become familiar with their human seem to consider them part of their herd, and become distraught when separated for long periods.
Guinea pigs can be kept in cages with low sides as they will rarely climb out. The cage should ideally be as large as possible – 7.5 square feet (0.7 square metres) for one guinea pig is about the minimum to allow space for moving about, exercise, and exploration, as they are naturally curious animals. If the guinea pig is kept in a smaller cage such as those sold in pet stores, it is essential to allow them daily time to move outside the cage (and this is always a good idea no matter how big the cage is.)
Guinea pigs do best in groups of two or more guinea pigs, as they have a herd mentality. However it is not advisable to keep guinea pigs and rabbits together as it is not uncommon for a guinea pig to be badly, if not fatally, injured by a rabbit suddenly kicking out with its paws or an overly romantic rabbit repeatedly trying to mount a guinea pig.
Domestic Guinea pigs' cages are often lined with wood shaving or a similar material; paper and aspen are generally considered safe bedding. Cedar and pine beddings which were common in the past, have harmful phenols (oils and scents) that can cause upper respiratory infections (which are fatal for many cavies). Many stores still sell cedar and pine beddings as safe for Guinea pigs, but there is growing pressure to stop the practice. A much safer bedding type is made from recycled newspapers.
A common cage type is the C&C, or coroplast and cubes cage, made from corrugated plastic and wire squares. These wire squares are generally a kind of unassembled shelving. These C&C cages are a much cheaper and spacious alternative to store-bought cages, and can be assembled in many creative ways.
They must be fed fresh vegetables and a commercial food made for guinea pigs. Rabbit food, for example, is not fortified with the vitamin C that guinea pigs must have in their diet. Like humans but unlike most other mammals, guinea pigs cannot synthesize their own vitamin C, but must obtain this vital nutrient from the food they eat in order to stay healthy. Also like humans, if guinea pigs cannot get enough vitamin C they will suffer from scurvy and ultimately die. Commercial vitamin C pills are also an excellent source. There are several approaches for feeding the pills, but in practice most guinea pigs quickly learn to like them. After a brief period of 'friendly-force-feeding', the animals start eating the pills from their owners' hands, making it an ideal source of essential vitamin C.
Guinea pigs are probably the smallest grass-eating mammals. Grass digestion requires a special digestive system: whereas most grass-eating mammals are quite large and have a long digestive tract, guinea pigs use a more unusual method: they practice coprophagy, the eating of one's own feces. They produce special soft pellets, called "cecotropes," which contain the B vitamins and bacteria required for proper digestion. They share this behaviour with rabbits.
Cavies also need unlimited timothy hay. However, alfalfa hay, which is richer, may be more appropriate for young guinea pigs. This provides roughage and fiber needed in their diet. A list of fresh food and more information about feeding fresh foods can be found at http://www.guinealynx.info/nutrition.html. Cavies should be fed approximately one cup of fresh vegetables daily. Favorites include apples, bananas, celery and green peppers.
Pelleted food is avialable under many different brand names, however most experts feel many brands are unacceptable to meet a cavy's needs. Alfalfa-based pellets (the most common pellet based food available) should be fed only to cavies one year of age or younger. Timothy-based should be fed to cavies older than one year.
Alfalfa, like other foods rich in calcium (such as spinach) should only be fed to adults in moderation. Being fed too much calcium-rich food can result in an animal developing problems with bladder stones and similar disorders.
Breeding is easy and males are not known to attack pups (however, females will breed on the day they give birth so it may not be wise to keep males with them at that time). Because of the long gestation period and the large size of the pups, pregnant females become extremely large. Pregnancy Toxemia is common and kills many pregnant females so you may not want to breed favorite pets. Breeding males produce a strong musk that smells much like bee's wax.
In scientific research
"Guinea pig" is often used as a metaphor for a subject of scientific experimentation. This notion persists even though guinea pigs are no longer commonly used as modern experimental animals. In the past they had been used to isolate different bacterial strains, but in modern labs they have been replaced by mice and rats, which reproduce more quickly.
Their main value to medical research is that they are one of the few animals which, like humans, cannot synthesize Vitamin C but must obtain it from diet.
Guinea pigs as food
Guinea pigs, or cuy, cuye, curí, were originally domesticated for their meat, but today are primarily raised as pets outside of Peru - this has led to some feeling that using cavies as a source of food is ethically wrong. This is a common occurrence in countries where the guinea pig is known mostly as a pet. It is similiar to the revulsion felt by Americans and Britons at the eating of horse meat in France, or the eating of dog in Korea. This disgust is a good example of cultural bias. See also taboo meat.
As food, the guinea pig is described as a combination of rabbit and the dark meat on chicken. It is high in protein (21%) and low in fat (8%). Due to the fact it requires much less room than traditional livestock and reproduce extremely quickly when compared to traditional stock animals, it can be raised as a source of food in an urban environment—something which most western livestock cannot do.
To this day, cavies continue to be a major part of the diet in Peru, particularly in the Andes Mountains highlands, where they are an important source of protein and a mainstay of Andean folk medicine. Peruvians consume an estimated 65 million Guinea pigs each year, and the animal is so entrenched in the culture that one famous painting of the Last Supper in the main cathedral in Cusco, Peru shows Christ and the twelve disciples dining on guinea pig.
- Piggie Planet
- Peter Gurney
- PetFinder provides listings of animals in need of adoption including guinea pigs
- IDRC guide to raising guinea pigs for meat or money
- Ananova article on Peruvian development of a "super edible" guinea twice the size of average cavies
- More about the Peruvian super-cavies (BBC Article)
- Report on Guinea Pigs by Livestock Research for Rural Development in Colombia
- Metafro research into the Guinea Pig as a meat producer
- Guinea Lynx provides medical information
- Information about Guinea pig socialization
- CavyPop has Guinea Pig information (also has forum if you need extra help)
- The Guinea Pig Compendium is an excellent source of information (including diet)
- Guinea Pig Care Articles and Pictures of Guinea Pigs on Petsyclopedia
- Cavy Cages (Information about Guinea pig caging - Coroplast and Cubes cages)
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