Rat

Published on December 2016 | Categories: Documents | Downloads: 44 | Comments: 0 | Views: 430
of 17
Download PDF   Embed   Report

Comments

Content


Rat
From Wikipedia, the free encyclopedia
This article is about the genus Rattus. For pet
rats, see Fancy rat. For other uses, see Rat
(disambiguation).
Rats
Temporal range:
Early Pleistocene –
Recent

The common brown
rat (Rattus norvegicus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Superfamily: Muroidea
Family: Muridae
Subfamily: Murinae
Genus: Rattus
Fischer de
Waldheim,
1803
Species
64 species
Synonyms
Stenomys Thomas,
1910
Rats are various medium-sized, long-
tailed rodents of the superfamily Muroidea. "True
rats" are members of the genus Rattus, the most
important of which to humans are the black
rat, Rattus rattus, and the brown rat, Rattus
norvegicus. Many members of other rodent
genera and families are also referred to as rats,
and share many characteristics with true rats.
Rats are typically distinguished from mice by their
size. Generally, when someone discovers a
large muroid rodent, its common name includes
the termrat, while if it is smaller, the name
includes the term mouse. The muroid family is
broad and complex, and the common
terms rat and mouse are
nottaxonomically specific. Scientifically, the terms
are not confined to members of
the Rattus and Mus genera, for example,
the pack rat and cotton mouse.
Contents
[hide]
 1 Species and description
 2 Pets
 3 Subjects for scientific research
o 3.1 Intelligence
o 3.2 Social intelligence
 4 Food
 5 Medicine
 6 Odor detection
 7 Rats as pests
 8 Rats as invasive species
 9 Culture
o 9.1 Asian cultures
o 9.2 European cultures
 9.2.1 Terminology
o 9.3 Fiction
 9.3.1 The Pied Piper
 10 Taxonomy of Rattus
o 10.1 Species
 11 See also
 12 References
 13 Further reading
 14 External links
Species and description
The best-known rat species are the black
rat (Rattus rattus) and the brown rat (Rattus
norvegicus). The group is generally known as
the Old World rats or true rats, and originated
in Asia. Rats are bigger than most Old
Worldmice, which are their relatives, but seldom
weigh over 500 grams (1.1 lb) in the wild.
The term "rat" is also used in the names of other
small mammals which are not true rats.
Examples include the North American pack rats,
a number of species loosely called kangaroo rats,
and others. Rats such as the bandicoot
rat(Bandicota bengalensis) are murine rodents
related to true rats, but are not members of the
genus Rattus. Male rats are called bucks,
unmated females are called does, pregnant or
parent females are called dams, and infants are
called kittens or pups. A group of rats is either
referred to as a pack or a mischief.


A rat in a city street


Idol of a rat in Patan (Nepal)
The common species are opportunistic survivors
and often live with and nearhumans; therefore,
they are known as commensals. They may cause
substantial food losses, especially in developing
countries.
[1]
However, the widely distributed and
problematic commensal species of rats are a
minority in this diverse genus. Many species of
rats are island endemics and some have become
endangered due to habitat loss or competition
with the brown, black or Polynesian rat.
Wild rodents, including rats, can carry many
different zoonotic pathogens, such
as Leptospira, Toxoplasma gondii,
and Campylobacter.
[2]
The Black Death is
traditionally believed to have been caused by the
micro-organismYersinia pestis, carried by the
tropical rat flea (Xenopsylla cheopis) which
preyed on black rats living in European cities
during the epidemic outbreaks of the Middle
Ages; these rats were used as transport hosts.
Other zoonotic diseases linked to pest rodents
include classical swine fever and foot-and-mouth
disease.
The average lifespan of any given rat depends on
which species is being discussed, but many only
live about a year due to predation.
The black and brown rats diverged from other Old
World rats during the beginning of
the Pleistocene in the forests of Asia.
Pets
Main article: Fancy rat


A domesticated rat
Specially bred rats have been kept as pets at
least since the late 19th century. Pet rats are
typically variants of the species brown rat,
but black rats and giant pouched rats are also
known to be kept. Pet rats behave differently from
their wild counterparts depending on how many
generations they have been kept as pets.
[3]
Pet
rats do not pose any more of a health risk than
pets such as cats or dogs.
[4]
Tamed rats are
generally friendly and can be taught to perform
selected behaviors.
Subjects for scientific research
Main article: Laboratory rat


A laboratory rat strain, known as a Zucker rat, is bred
to be genetically prone to diabetes, the
same metabolic disorder found among humans.
In 1895, Clark
University in Worcester,Massachusetts (United
States) established a population of domestic
albino brown rats to study the effects of diet and
for other physiological studies. Over the years,
rats have been used in many experimental
studies, which have added to our understanding
of genetics,diseases, the effects of drugs, and
other topics that have provided a great benefit for
the health and well-being of humankind.
Laboratory rats have also proved valuable in
psychological studies of learning and other
mental processes (Barnett, 2002), as well as to
understand group behavior and overcrowding
(with the work of John B. Calhoun on behavioral
sink). A 2007 study found rats to
possess metacognition, a mental ability
previously only documented in humans and some
primates.
[5][6]

Domestic rats differ from wild rats in many ways.
They are calmer and less likely to bite; they can
tolerate greater crowding; they breed earlier and
produce more offspring; and
their brains, livers, kidneys, adrenal glands,
and heartsare smaller (Barnett 2002).
Brown rats are often used as model
organisms for scientific research. Since the
publication of the rat genome sequence,
[7]
and
other advances, such as the creation of a
rat SNP chip, and the production of knockout
rats, thelaboratory rat has become a useful
genetic tool, although not as popular as mice.
When it comes to conducting tests related to
intelligence, learning, and drug abuse, rats are a
popular choice due to their
high intelligence, ingenuity,aggressiveness,
and adaptability. Their psychology, in many ways,
seems to be similar to humans. Entirely
newbreeds or "lines" of brown rats, such as
the Wistar rat, have been bred for use in
laboratories. Much of the genome of Rattus
norvegicus has been sequenced.
[8]

Intelligence


A rat in a suburb of Vancouver
Because of the ability to learn, rats were early on
investigated to see whether they may
exhibit general intelligence, expressed by the
presence of a g factor, like larger or more
complex animals. A 1929 study did not find a g
factor,
[9]
nor did a 1990 work;
[10]
a 1935
study
[11]
did:
Robert Thorndike, for example, provided strong
evidence for g in rats by the use of a variety of
tests such as mazes, problem-solving tasks, and
simple avoidance conditioning (Thorndike 1935).
Performances tended to correlate across tasks,
with stronger associations found between mazes
and problem-solving than with simple avoidance
tasks. Thorndike (1935) also reviewed a dozen
earlier studies which also suggested that the
highest correlations are found between more
complex problem-solving tasks. However, it
should be noted that there were other
contemporary studies that found split or near
zero-order correlation matrices for other
populations of rats across cognitive batteries (see
Royce 1950).

[12]

In 1993, Anderson measured rat performance
and factor analysis produced a g, and also
correlations with rat brain size
[13]
(as in humans
and primates). Locurto & Scanlon
1998,
[14]
Matzel et al. 2003,
[15]
Matzel et
al. 2004,
[16]
Kolata et al. 2009
[17]
and Matzel et
al. 2011
[18]
replicated the factor (but did not
investigate brain size); 2003 Locurtoet al., 2006
Locurto et al. in contrast found their factor
analysis giving 4 factors rather than 1.
Social intelligence
A 2011 controlled study found that rats are
actively prosocial. They demonstrate altruistic
behaviour to other rats in experiments, including
freeing them from cages. When presented with
readily available chocolate chips, test subjects
would first free the caged rat, and then share the
food. All female rats in the study displayed this
behaviour, while 30% of the males did not.
[19]

Food


Rat meat dishes in Yangshuo,Guangxi, China
Rat meat is a food that, while taboo
[20][21]
in some
cultures, is a dietary staple in others. Taboos
include fears of disease or religious prohibition,
but in many places, the high number of rats has
led to their incorporation into the local diets.
In some cultures, rats are or have been limited as
an acceptable form of food to a particular social
or economic class. In the Mishmi culture of India,
rats are essential to the traditional diet, as Mishmi
women may eat no meat except fish, pork, wild
birds and rats.
[22]
Conversely,
the Musaharcommunity in north India has
commercialised rat farming as an exotic
delicacy.
[23]
In the traditional cultures of the
Hawaiians and the Polynesians, rat was an
everyday food for commoners. When feasting,
the Polynesian people of Rapa Nui could eat rat
meat, but the king was not allowed to, due to the
islanders' belief in his "state of sacredness"
called tapu.
[24]
In studying precontact
archaeological sites in Hawaii, archaeologists
have found the concentration of the remains of
rats associated with commoner households
accounted for three times the animal remains
associated with elite households. The rat bones
found in all sites are fragmented, burned and
covered in carbonized material, indicating the rats
were eaten as food. The greater occurrence of rat
remains associated with commoner households
may indicate the elites of precontact Hawaii did
not consume them as a matter of status or
taste.
[25]

Bandicoot rats are an important food source
among some peoples in Southeast Asia, and the
United Nations Food and Agriculture
Organization estimated rat meat makes up half
the locally produced meat consumed in Ghana,
wherecane rats are farmed and hunted for their
meat. African slaves in the American South were
known to hunt wood rats(among other animals) to
supplement their food rations,
[26]
and Aborigines
along the coast in southern Queensland,
Australia, regularly included rats in their diet.
[27]

Ricefield rats (Rattus argentiventer) have
traditionally been used as food in rice-producing
regions such as Valencia, as immortalized
by Vicente Blasco Ibáñez in his novel Cañas y
barro. Along with eel and local beans known
asgarrafons, rata de marjal (marsh rat) is one of
the main ingredients in traditional paella (later
replaced by rabbit, chicken and
seafood).
[28]
Ricefield rats are also consumed in
the Philippines, the Isaan region of Thailand,
andCambodia. In late 2008, Reuters reported the
price of rat meat had quadrupled in Cambodia,
creating a hardship for the poor who could no
longer afford it.
Elsewhere in the world, rat meat is considered
diseased and unclean, socially unacceptable, or
there are strong religious proscriptions against
it. Islam and Kashrut traditions prohibit it, while
both the Shipibo people of Peru andSirionó
people of Bolivia have cultural taboos against the
eating of rats.
[29][30]

Rats are a common food item for snakes, both in
the wild, and as pets. Captive-bred ball pythons,
in particular, are fed a diet of mostly rats. Rats
are available to individual snake owners, as well
as to large reptile zoos, from many suppliers. In
Britain, the government in 2007 ruled out the
feeding of any live mammal to another animal.
The rule says the animal must be dead (frozen)
then given to the animal to eat. The rule was put
into place mainly because of the pressure of
the RSPCA and people who found it cruel.
Medicine
Rats can serve as zoonotic vectors for certain
pathogens and thus cause disease, such
as Lassa
fever, leptospirosisand Hantavirus infection.
Odor detection
Rats have a keen sense of smell and are easy to
train. These characteristics have been employed,
for example, by the Belgian non-governmental
organization APOPO, which trains rats
(specifically African giant pouched rats) to
detect landmines and
diagnose tuberculosis through smell.
[31]

Rats as pests
Rats have long been considered deadly pests.
Once considered a modern myth, the rat
flood in India has now been verified. Indeed
every fifty years, armies of bamboo rats descend
upon rural areas and devour everything in their
path.
[32]
Rats have long been held up as the chief
villain in the spread of the Bubonic
Plague,
[33]
however recent studies show that they
alone could not account for the rapid spread of
the disease through Europe in the Middle
Ages.
[34]
Still, the Center for Disease
Control does list nearly a dozen
diseases
[35]
directly linked to rats. Most urban
areas battle rat infestations. Rats in New York
City are famous for their size and prevalence.
The urban legend that the rat population in
Manhattan equals that of its human population (a
myth definitively refuted by Robert Sullivan in his
book "Rats") speaks volumes about New Yorkers'
awareness of the presence, and on occasion
boldness and cleverness, of the rodents.
[36]
New
York has specific regulations for getting rid of
rats—multi-family residences and commercial
businesses must use a specially trained and
licensed exterminator.
[37]
Places to look for rat
infestations are around pipes, behind walls and
near garbage cans. Effective rat control requires
municipal workers and individuals to work
together.
Rats as invasive species
When introduced into locations where rats
previously did not exist they cause a huge
amount of environmental degradation. Rattus
rattus, the black rat, is considered to be one of
the world's worst invasive species.
[38]

As part of island restoration some islands have
had their rat populations eradicated to protect or
restore the ecology.Hawadax Island, Alaska was
declared rat free after 229 years and Campbell
Island, New Zealand after almost 200
years. Breaksea Island in New Zealand was
declared rat free in 1988 after an eradication
campaign based on a successful trial on the
smaller Hawea Island nearby.
The Canadian province of Alberta is notable for
its history of being free of the Norwegian rat. A rat
control program was created after they started
making inroads there during World War II. The
program still actively employs patrols along its
border with Saskatchewan.
Culture
Ancient Romans did not generally differentiate
between rats and mice, instead referring to the
former as mus maximus (big mouse) and the
latter as mus minimus (little mouse).
[citation needed]

On the Isle of Man (a dependency of the British
Crown), there is a taboo against the word
"rat".
[citation needed]

Asian cultures
Main article: Rat (zodiac)
The rat (sometimes referred to as a mouse) is the
first of the twelve animals of the Chinese zodiac.
People born in this year are expected to possess
qualities associated with rats, including creativity,
intelligence, honesty, generosity, ambition, a
quick temper and wastefulness. People born in a
year of the rat are said to get along well with
"monkeys" and "dragons", and to get along poorly
with "horses".


The indigenous rats are allowed to run freely
throughout the Karni Mata Temple.
In Indian tradition, rats are seen as the vehicle
of Ganesha, and a rat's statue is always found in
a temple of Ganesh. In the northwestern Indian
city of Deshnoke, the rats at the Karni Mata Tem
v

Sponsor Documents

Or use your account on DocShare.tips

Hide

Forgot your password?

Or register your new account on DocShare.tips

Hide

Lost your password? Please enter your email address. You will receive a link to create a new password.

Back to log-in

Close