The gerbil got its name as a diminutive form of "jerboa", an unrelated group of rodents occupying a similar ecological niche. Gerbils are typically between 150 and 300 mm (6 and 12 in) long, including the tail, which makes up about half of their total length. One species, the great gerbil, Rhombomys opimus, originally native to Turkmenistan, can grow to more than 400 mm (16 in). The average adult gerbil weighs about 70 grams (2+1⁄2 ounces). One species, the Mongolian gerbil Meriones unguiculatus, also known as the clawed jird, is a gentle and hardy animal that has become a popular small house pet. It is also used in some scientific research.