What is the Size of a Rat?
WouterThe size of a rat depends on several factors, including its species, age, and gender. Adult rats are bigger than baby rats, and most males are heavier than females. The size of a rat is also affected by its diet and environment. A well-fed rat grows larger than a poorly-fed one.
Rats have two distinct uterine bodies and separate urethral and vaginal openings. They lose the vaginal closure membrane at puberty, but the inguinal canal is left open throughout life. They also have a penis, which is associated with their external genitalia. Their mammary tissue is also widely distributed, and may extend into the lateral and dorsal abdominal regions.
Rats have a gestation period of approximately 21 days. The male rat is slower to mature, and the gestation period is between 22 and 23 days. The newborn rat is about two to four inches long, and weighs between five and eight grams. Rats breed throughout the year. Some tropical species breed only during the wet season.
The size of a rat varies greatly, and it depends on the species. The largest species is the Bosavi woolly rat, which was discovered in Papua New Guinea in 2009. It is approximately the size of a cat and weighs 3.3 pounds (1.5 kilograms). The Osgood’s Vietnamese rat can grow to eight inches long and weigh up to four pounds.
