Cavy

Cavy is a general name given to the members of the family Caviidae, the cavy meaning often is more commonly associated with the member called Guinea pig. The guinea pig is commonly known as the cavy. The cavy term is more commonly used in a day to day conversation, while the term Guinea pig is more scientifically correct and is used to define cavy scientifically. The main reason for this is that the cavy meaning is often confused with the family Caviidae. The scientific name of the cavy or guinea pig is Cavia porcellus. Cavia porcellus is defined as the species of rodent that is classified under the family Caviidae.

The article focuses on the taxonomical classification, general features, life history and evolution. The article also discusses the reproduction pattern, diet and behaviour of the guinea pigs.

What is a Cavy?

A cavy can be defined as a guinea pig, the term cavy meaning also sometimes refers to the family under which these animals are classified. Guinea pigs are a species of rodents. The guinea pigs are also sometimes known as domesticated cavy. Although the name suggests some sort of relation between guinea and pigs, the animal is not native to Guinea and is not even related to the pigs.  The guinea pigs are large rodents, with very friendly behaviour. They are a popular pet in western countries, they were introduced in England by traders since then are considered domesticated rodents. It is also very highly unlikely to find a guinea pig in the wild.

The physical features of the cavy can be defined as a short animal, they have heavy bodies and large heads. Another characteristic feature is that they have no visible tails, also the eyes are very large, they have a small ears. The guinea pigs are considerably large species of rodent classified under the family, the bodyweight of a cavy can range up to  500 to 1,500 grams, the length of the body is merely 20 to 40 cm long. The guinea pigs are found in various colours, the most common colours in which the animal is black, brown, white and grey. An interesting fact about the guinea pigs is that there are no records of the animal to be found in the wild, it is estimated that they are domesticated nearly more than 3,000 years ago in Peru. guinea pigs are also used as a research subject in various scientific researches. 

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History of Guinea Pigs

It is well established now that cavy is not found in the wild, the phylogenetic study and research using the molecular markers indicates that cavy descended from similar species like  C. aperea, C. fulgida, and C. tschudii , these species are still found in some parts of South America. The molecular marker-based study revealed the highest percentage of genetic similarity with the C. tschudii, species. The morphological similarity was found in the skull and skeletal system. It is also estimated the species of guinea pigs developed by selective breeding of these ancestor species. 

These ancestor species of the cavy or guinea pig are social animals, similar to the guinea pig itself. They are commonly seen living in herds and groups. Guinea pig and its ancestor species are termed as crepuscular, the term can be defined as the animals that are most active during the twilight. This pattern is still very evident in guinea pigs. The term cavy meaning may seem to refer to have some kind of relation with caves, to some degree this etymology is true. Guinea pigs, as well as the ancestor species, are generally found living in small caves and burrows that resemble to cave. Although it is important to note that these animals do not build their own burrow, they rather live in the burrows made by other animals generally other rodent species.

The common etymology of “guinea pig” is very debatable as it neither has any relation to pig or guinea. Another important historical aspect of the animal is their introduction into western civilization. The earliest records of domestication date back to nearly 3000 years ago in countries like Peru. the guinea pigs were brought by the traders from South America to Europe, the earliest known record of the animal brought to Europe dates back to 15 th century, to be specific it dates back to 1547. The introduction of these animals into England gained popularity as they were gifted to British royals as exotic pets. Since then the popularity of the cavy as a pet has not seen a decline.

Taxonomic Classification

Taxonomic classification refers to the classification of animals based on their similarity and dissimilarity. The need for taxonomic classification arises to have a better understanding of the nature of the animal, the phylogenetic relationship of the animal and to develop a better understanding of the evolutionary course and adaptation of the animal. The taxonomic classification of the cavy is mentioned below.

Guinea pigs belong to the kingdom Animalia, the kingdom mainly consists of the members that are eukaryotic multicellular in nature. Another common requirement to be classified under this kingdom is they can uptake organic matter, the metabolic waste of respiration is carbon dioxide which is exhaled out. Another important characteristic unique to the members of this kingdom is the formation of the Blastula during the early embryonic developmental stage. The blastula is the 18 to 32 celled stage of an organism, it is marked by the formation of the blastocoel. Bastocoel is a fluid-filled cavity that forms a different layer of tissue in a multicellular organism. All these features hold completely true for the cavy.

The kingdom is further classified as Phylum, guinea pig belonged to the phylum called Chordata. There are 5 main characteristics required to be categorized under this phyla are as follows, the presence of the notochord, the presence of the dorsal hollow nerve cord, the presence of endostyle or thyroid,  presence of pharyngeal slits, and a post-anal tail. The animals that belong to this phylum are generally categorized as highly evolved animals.

The phylum is further categorized into order, cavy belongs to the order Mammalia. The most important characteristic feature of this phylum is the ability to give birth to young ones. Another very important feature is that they possess the mammary gland which provides nutrition to the young progeny of tyhe animal. They are also marked by the presence of a neocortex, fur or hair, and three middle ear bones. The neocortex is a part of the brain it is important because it represents the highly developed state of the nervous system. The guinea pigs share almost all the characteristics required to be classified as mammals.

Guinea pigs belong to the order called Rodentia, one of the most important features of the members of the order is the presence of the incisors on the jaws, the incisors are the ever-growing in the members of this order. The rodents have only a single pair of incisors in th upper jaw and lower jaw. Rodents are considered as placental mammals. Another feature of the rodent includes the morphology of the body which is described as having a robust body with short limbs and long tails. The mating system in rodents varies from species. They follow almost all the mating patterns like monogamy, polygamy, polyandry and, promiscuity.

The order is further divided into families, the guinea pigs belongs to the family called Caviidae. The cavy meaning also associated with the family as sometimes the family is also referred to as cavy family. The characteristic feature of this family is morphology. The members of this family share a degree of similarity with rabbits. The body of the rodents that belong to this family, like cavy, have a small body with a heavy head. A unique feature of members of this family is the absence of the visible tail. All these features hold completely true for guinea pigs.

The family Caviidae is divided into three subfamilies, these subfamilies are as follows,

1.  Caviinae

2.  Dolichotinae

3.  Hydrochoerinae

The order is further classified into genus and species. The guinea pigs belong to the genus called Cavia. It is important to note that the genus is classified under the subfamily called  Caviinae, the subfamily is a category that belongs to the family called Caviidae. The most important species that are categorized under this genus is the guinea pig. The scientific name of the cavy is referred to as Cavia porcellus, the scientific name represents the name of genus followed by the species. 

Morphological Features of Cavy

The cavy or guinea pigs are similar to rabbits. They have a robust but small body. The head is heavy in comparison with other rodents. The eyes are big accompanied by short ears. One of the most important features is the presence of a single pair of incisors in the upper and lower jaws. The feet are not very long, the feet are often seen as hairless. The sole of the feet is hairless with the unique feature of short sharp claws. The number of toes varies in the forelimb and hindlimb. The forelimb has 4 toes while the hind feet have 3 toes. 

The body colour of the guinea pig is dependent on the colour of the fur. The texture and fur are also used to distinguish different types of guinea pigs. The colour of the furs are generally seen in the following colours, white, cream, tan, reddish or chocolate brown, black, or a combined pattern. The weight of the guinea pig can range from 500 to 1,500 grams which are roughly about 1 to 3 pounds. The complete length of the body can range up to y 20 to 40 cm which is approximately about 8 to 16 inches long.

An interesting point about the guinea pig is that they are not sexually dimorphic, that is defined as the morphological difference in the male and the female members of the species. The male, as well as the female species, do not have much morphological difference. both the male and female genitalia are located very close to the anus. The female genitalia has only a distinguishing morphological feature that is the presence of the "Y"-shaped configuration formed from a vulvar flap. The male gametes are stored in the testes, the testes are stored in the scrotum. The scrotal poch is visible externally. The male genitalia share resemblance with the penis, with the penis and anus forming a similar shape, the penis will protrude if pressure is applied to the surrounding hair anterior to the genital region.

Diet of Cavy

Since cavy is a predominately domesticated species, they are adapted to grains as part of the diet. A unique feature that is observed in the cavy is that they do not require water to sustain their life if they are supplied with highly moist food. The animal predominantly feeds on grass especially grass called grass hay, such as timothy hay.  Alfalfa is also a major constituent of their diet. An interesting fact about guinea pigs diet and metabolism is their inability to synthesize vitamin C. since they can not synthesize vitamin C, it is provided by the diet. The vitamin rich diet includes the following, guinea pigs require about 10 mg of vitamin C daily fresh, raw fruits and vegetables, for example, broccoli, apple, cabbage, carrot, celery, and spinach.

An important fact about the diet of guinea pigs is that they meet the requirement of vitamins especially vitamin B12 and other fibres by ingesting their,  cecotropes (or caecal pellets), which is also found in rabbits. The faeces from the night is directly ingested from the anus. This is primarily done to support their nutrient requirement.

Reproduction

Cavy is a sexually reproducing organism. It is important to note that these organisms are classified as placental mammals, that they not only give birth to their progeny but also the embryonic development that occurs within the female body and the nutrients required for development is provided by the placenta. The placenta thus serves as a connecting tube between mother and fetus and provides nutrients from the female body to the fetus. 

The fertilization is internal and the organism follows sexual reproduction. Some degree of parental care is present in this organism as they provide lactation to tyhe progeny to sustain the early life. An interesting fact about reproduction is that the guinea pigs givers birth to precocial progeny, that is the progeny are well-developed with hair, teeth, claws, and partial eyesight

Sexual maturity is attained at the age of  3–5 weeks, the sexual maturity in females is attained around 4 weeks. The gestation period of the mammal can range from 59 days (1.9 months) to 72 days (2.4 months), with an average of 63–68 days. The litter size of the guinea pig can have 1 to 6 offsprings with an average of 3 offsprings in a litter. A litter is defined as the birth of multiple progenies by the same mother during a single pregnancy.

A unique feature called alloparental care is observed in the cavy. It refers to providing parental care and protection to the young ones that are not directly genetically related to the adult animal.  There are some reported cases of stillbirths, the primary reason for this is the oversize and obese pup development during embryonic development. 

Social Behaviour

Cavies are generally considered friendly animals, they have shown an increased level of emotional intelligence. They can live in herds or can live in solitary. Research has proved that they have exceptional memory, they can remember the complex routes of food sources and can retain the information for months. One of their strongest skill is the ability to sense danger, they can sense danger from a distance. It is common for the cavy to be part of social grooming as this behaviour is also seen in the other rodent species.

Importance

It is now a well understood fact that the cavy is a very popular pet. The popularization of this animal became evident during the 15th century and has not seen a decline. Apart from serving as a pet, the animal is also bred for its meat. The cavy meat has low cholesterol and high protein content. It is believed to be a delicacy of countries like Peru and Bolivia. Another important use is that they are used as subjects for biological researches. 

In conclusion, it can be said that cavy meaning is largely associated with the animal called guinea pig which is commonly referred to as cavy. These animals rae quite popular for their adorable looks. The early evidence of domestication of these animal dates back to 3000 years ago in Peru. in popularity in western society as the pet was established by traders that considered cavy as exotic pets and gifted it to royals. The cavy shares most of tyhe morphological features with rabbits, they belong to the order Rodentia, and are considered rodents. Cavy is not only a domestic pet but serves as the subject of research for the study of anatomy, nutrition, genetics, toxicology, pathology, serum development, and other research programs.