As you can see below there is a full definition of the term Rodentia,
if you are interested, like me, then once you have read the preamble you
can click on one of the links above to take you to the page which most
concerns you. Also included above are some none-rodent types, which ,
thanks to do-gooders releasing them, various imports and escapes, have
become a major problem to indigenous species e.g. Mink...!
Rodentia: (rats, mice, beavers, squirrels, guinea pigs, capybaras,coypu)
rodents, or Rodentia, are the most abundant order of mammals. At present,
over a quarter of the families, 35 percent of the genera, and 50 percent
of the species of living mammals are rodents. Probably an even higher
percentage of individuals are rodents, for they tend to be small animals
with dense populations. They are one of the few groups of animals that
flourish in close association with men. Some, such as squirrels, live
independently but fairly successfully near humans. Others, such as the
house mouse (Mus musculus) and black and Norway rats (Rattus
rattus and R. norvegicus), have adapted themselves to human civilization,
and live everywhere that man does. These two rats (and the Polynesian
rat, Rattus exulans, of Australia and Oceania) have travelled
in ships and boats of all sizes, and have populated the entire habitable
world, especially near human habitations (see below for differences).
GENERAL FEATURES: All
rodents possess one pair of upper and one of lower incisors, growing throughout
life, with the enamel restricted to a band on the front side of the teeth.
Behind this is a large gap (diastema) followed by two to five cheek teeth.
The jaw articulation is so arranged that when the cheek teeth are in use,
the incisors do not meet, and vice versa. The incisors grow continuously,
and must be worn off equally fast, or the whole gnawing mechanism is ruined.
Because of the necessity to abrade these incisors, rodents spend a considerable
amount of time gnawing hard objects.
rodents are small. Some mice and dormice are among the smallest of living
mammals, adults being as small as 75 millimetres (three inches) long,
including the tail, and weighing as little as 20 grams (0.7 ounce). The
largest living rodent is the South American capybara (Hydrochoerus
hydrochoeris), reaching over 1.3 metres (four feet) in length
and as much as 50 kilograms (about 110 pounds) in weight. A fossil rodent
recently described from Uruguay is reported to have had a skull as large
as that of a bull and a body bulk as large as that of a wild boar.
are of major economic importance, primarily as consumers of the grains
that are the basic foodstuff for man. It has been estimated that rats
and mice destroy up to one-third of grain crops under conditions of heavy
infestation. Burrowing rodents may damage root crops. The muskrat (Ondatra
zibethica) and nutria (Myocastor coypus), introduced
into Europe as fur sources, have escaped and spread over much of Europe
between the Baltic and the Alps. Their burrows, particularly in canal
banks, have been a major source of damage to the drainage system, most
especially in The Netherlands. A number of rodents serve as reservoirs
for human diseases, such as bubonic plague, tularemia, scrub typhus, and
others. The plague that ravaged Europe during the mid-14th century was
transmitted by fleas from rats to humans.
rodents (beaver, muskrat, chinchilla, nutria, squirrel) produce fur useful
to man. All but beaver and squirrel have been domesticated for this purpose.
Albino mice and rats, hamsters, and guinea pigs are widely used as laboratory
animals for biological and medical purposes. Guinea pigs were domesticated
by the Incas for food; a few kinds of rodent have been raised as pets.
occur naturally in all parts of the land where there is an adequate food
supply and are found in essentially all terrestrial habitats. They range
from well above the Arctic Circle to the southern tips of Africa and South
America and were the only terrestrial placental mammals, other than bats,
to reach Australia before the arrival of man. Many rodents have successfully
adapted to difficult environments such as deserts. Many rodents have broad
climatic tolerances, an example being the North American porcupine, which
is found from the Arctic Circle to central Mexico and from the Atlantic
to the Pacific. Most are quadrupedal scamperers, but they generally have
much freedom of use of their forefeet in manipulating food; many are burrowers,
spending most of their life underground; some are ricochetal, leaping
on their hind legs; flying squirrels use skin membranes to glide from
one tree to another; a few (beaver, muskrat, water vole, nutria) have
become amphibious in habit, living in freshwater streams and ponds; and
a number of South American rodents are cursorial (running) animals.
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