Hamsters are rodents (order Rodentia) belonging to the subfamily Cricetinae, which contains 19 species classified in seven genera.[1][2] They have become established as popular small pets.[3] The best-known species of hamster is the golden or Syrian hamster (Mesocricetus auratus), which is the type most commonly kept as a pet. Other hamster species commonly kept as pets are the three species of dwarf hamster, Campbell’s dwarf hamster (Phodopus campbelli), the winter white dwarf hamster (Phodopus sungorus) and the Roborovski hamster (Phodopus roborovskii).
Hamsters feed primarily on seeds, fruits, vegetation, and occasionally burrowing insects. In the wild, they are crepuscular: they forage during the twilight hours. In captivity, however, they are known to live a conventionally nocturnal lifestyle, waking around sundown to feed and exercise.[4] Physically, they are stout-bodied with distinguishing features that include elongated cheek pouches extending to their shoulders, which they use to carry food back to their burrows, as well as a short tail and fur-covered feet.
Classification
Taxonomists generally disagree about the most appropriate placement of the subfamily Cricetinae within the superfamily Muroidea. Some place it in a family Cricetidae that also includes voles, lemmings, and New World rats and mice; others group all these into a large family called Muridae. Their evolutionary history is recorded by 15 extinct fossil genera and extends back 11.2 million to 16.4 million years to the Middle Miocene Epoch in Europe and North Africa; in Asia it extends 6 million to 11 million years. Four of the seven living genera include extinct species. One extinct hamster of Cricetus, for example, lived in North Africa during the Middle Miocene, but the only extant member of that genus is the European or common hamster of Eurasia.
Relationships among hamster species
Neumann et al. (2006) conducted a molecular phylogenetic analysis of 12 of the above 17 species using DNA sequence from three genes: 12S rRNA, cytochrome b, and von Willebrand factor. They uncovered the following relationships:[5]
History
Although the Syrian hamster or golden hamster (Mesocricetus auratus) was first described scientifically by George Robert Waterhouse in 1839, researchers were not able to successfully breed and domesticate hamsters until 1939.[3] The entire laboratory and pet populations of Syrian hamsters appear to be descendants of a single brother–sister pairing. These littermates were captured and imported in 1930 from Aleppo in Syria by Israel Aharoni, a zoologist of the University of Jerusalem.[8] In Jerusalem, the hamsters bred very successfully. Years later, animals of this original breeding colony were exported to the United States, where Syrian hamsters became a common pet and laboratory animal. Comparative studies of domestic and wild Syrian hamsters have shown reduced genetic variability in the domestic strain. However, the differences in behavioral, chronobiological, morphometrical, hematological, and biochemical parameters are relatively small and fall into the expected range of interstrain variations in other laboratory animals.[9]
Description
Hamsters are typically stout-bodied, with tails shorter than body length, and have small, furry ears, short, stocky legs, and wide feet. They have thick, silky fur, which can be long or short, colored black, grey, honey, white, brown, yellow, red, or a mix, depending on the species. Two species of hamster belonging to the genus Phodopus, Campbell’s dwarf hamster (P. campbelli) and the Djungarian hamster (P. sungorus), and two of the genus Cricetulus, the Chinese striped hamster (C. barabensis) and the Chinese hamster (C. griseus) have a dark stripe down their heads to their tails. The species of genus Phodopus are the smallest, with bodies 5.5 to 10.5 cm (2.2 to 4.1 in) long; the largest is the European hamster (Cricetus cricetus), measuring up to 34 cm (13 in) long, not including a short tail of up to 6 cm (2.4 in).
The hamster tail can be difficult to see, as it is usually not very long (about 1⁄6 the length of the body), with the exception of the Chinese hamster, which has a tail the same length as the body. One rodent characteristic that can be highly visible in hamsters is their sharp incisors; they have an upper pair and lower pair which grow continuously throughout life, so must be regularly worn down. Hamsters are very flexible, but their bones are somewhat fragile. They are extremely susceptible to rapid temperature changes and drafts, as well as extreme heat or cold.