Rats are rodents which are mostly found in urban dwellings and they constitute one of the most parasitic pests now. Although there are lots of species of rodents, there are essentially two kinds of rats, Rattus norvegicus; the Norway/street/common/home rats that are generally brown in color and rattus the roof rats that are black in color. The brown rats are considered to have originated from northern China and have since spread across all of the countries in the continents. They are easily adaptable to any environment - the chief reason for their success in distributing - and can survive longer without water than a camel.
Biology: Brown rats begin small at birth, but by 12 weeks, the average male brown rat has become larger than a female brown rat. Despite the fact that the female begins her puberty earlier between 34-38 days compared to the male's 39-47 days; the male testes descend between 15-50 days. Menopause for the females arrive in between 450-540 days.
Appearance: The rat's tail is among its main features and its functions is to offer balance when climbing ropes or walking across fences and tree branches. The tail of a rat doesn't have any fur but has many blood vessels that give it a thermoregulatory function; it will help to control the rat's temperature. When a rat is cold, its tail shrinks/constricts limiting its blood circulation; the blood that flows to the tail, the more the body conserve warmth. And, Yes! Rats DO have bones!
Rats have only two types of teeth, canines and molars. The incisors that are four (two up and down) are used for gnawing and they grow throughout the lifespan of the rat. The first pair of molars erupt at 19 days, the next group grow in 21 days and the rest of the set grow in 35 days.
The eyes of a rat open 12-14 days after birth and are like humans but they essentially have smaller eyes than humans and their vision is poorer (poor eyesight acuity).
Habitat: The brown rats are largely burrowers. They are generally located outside the walls of houses, in gutters or under boards and in bushes. Black rats on the other hand, are largely found in roofs, attics, and on trees such as palm and cypress as they favor an elevated habitat. They also reside in tall grasses and shrubs.
Diet: Rats will feed on almost anything including carcasses of their own kind and dropped fruits but the brown rats are more omnivorous.
Behavior: Rats display aggression particularly when threatened and might bite, fight and chase the instigator. Amongst themselves, the more powerful ones become dominant while the poorer ones are subordinate. Males mate with females in order of the social dominance. Thus a poor male seldom gets to mount a lady.
The brown rat is nocturnal, a great swimmer, and can climb high in addition to burrow. They also have metacognition, a psychological ability previously found in humans and some primates.
In appropriate conditions, rats can breed all year round, a female rat can create up to five litters a year - a mess usually has 6-14 rats. The gestation period is generally between 21-26 days, although 26 days is rare and the average is in fact 22 days. The litter declines in number when the female is close menopause at about 18 months old.
Brown and black rats can partner but the infants rarely live, the embryos are reabsorbed, aborted or born dead. The average lifespan of a rat is just two to three years although most die before one year. Brown rats reside in hierarchical groups as well as the lowest in social order would be the first to die when food is in short supply. If half of the population becomes ruined, they reproduce quickly to restore the population level.