There are 87 known species and 14 genera of gerbil. The Mongolian gerbil (Meriones unguiculatus), also referred to as the desert rat, originates from Mongolia and Northern China and is an extremely good digger, digging with its front paws and kicking debris away with its strong hind legs.
Full-grown Mongolian gerbils reach a length of 12-14 cm from nose to the base of the tail and the tail is approximately 8-10 cm in length. The head is broad and short and the tail is covered in fur with a small tuft at the end. The Mongolian gerbil is a sociable pet appreciating the company of others. Gerbils are active both in the day and night, sleeping at intervals for a couple of hours. Gerbils are good natured and inquisitive making them extremely good pets. The average lifespan is 3-5 years although they can live longer.
| Color Standard | Guard Hairs | Undercoat | Eyes | Nose |
| Albino | White to cream | White to cream | Ruby red | Pink |
| Black | Black | White to slight golden | Black or near black | Black |
| Black Sable | Dark ash blackish brown | White to cream | Dark brown or near black | Blackish brown |
| Champagne | Tan | White to cream | Light to dark burgundy to dark brown | Beige or pink |
| Chocolate | Warm milk chocolate | White | Brown or dark burgundy | Beige or pink |
| Dark-eyed White | White to cream | White to cream | Burgundy | Pink |
| Sable | Deep brown | White to cream or light golden | Brown or near black | Light or mottled brown |