Both gerbils and rats belong to the expansive Order Rodentia, meaning they share the characteristic of continuously growing incisor teeth. However, this is where their close relationship ends. Gerbils and rats represent distinct evolutionary paths that have resulted in significant differences in their anatomy, behavior, and care requirements. Understanding these distinctions reveals two unique species adapted to vastly different environments.
Defining the Taxonomic Split
Both gerbils and rats are grouped under the Order Rodentia, yet they diverge at the family and subfamily levels. The typical pet rat, the Fancy Rat (Rattus norvegicus), falls under the family Muridae, commonly known as the Old World rats and mice. Gerbils, such as the common Mongolian Gerbil (Meriones unguiculatus), are also classified within the family Muridae, but they are separated into their own distinct subfamily, the Gerbillinae.
This taxonomic separation signifies a major evolutionary split, demonstrating that gerbils are not simply a species of rat. Gerbils are desert-adapted rodents that evolved in the arid and semi-arid regions of Africa, India, and Asia, a very different environment from the cosmopolitan origins of the rat. The Gerbillinae subfamily includes approximately 110 species, all of which share certain adaptations for survival in harsh, dry climates.
Key Physical and Physiological Distinctions
Adult rats are significantly larger and heavier than gerbils, with the average gerbil weighing 60 to 100 grams, compared to a rat’s typical weight of 350 to 650 grams. Gerbils possess a slender body shape and long, powerful hind legs, which are specialized for hopping and digging in sandy habitats. Rats, in contrast, have a broader, lower body profile and utilize all four limbs equally for running and climbing.
Their tails also serve different purposes. The gerbil’s tail is fully furred and often tipped with a small tuft of hair, providing balance during quick, agile movements. The rat’s tail is long, mostly hairless, and covered in fine scales, functioning primarily as a prehensile limb for climbing and thermoregulation. Gerbils show remarkable adaptations to their desert origin, requiring very little water and producing highly concentrated urine to conserve body fluids. This water-efficient physiology is absent in rats.
Differences in Temperament and Domestic Care Needs
Gerbils are active during the day and night, exhibiting crepuscular behavior with bursts of activity at dawn and dusk, while rats tend to be more nocturnal. Gerbils are instinctively driven to burrow and dig, a behavior that requires deep bedding, often 10 to 12 inches, for their well-being in captivity. Rats are accomplished climbers and prefer vertical space in their enclosures, utilizing ramps and platforms.
Both species are highly social and thrive when housed in same-sex pairs or groups, but their interaction styles differ significantly. Gerbils are usually viewed as more of a “watch and observe” pet, as they are fast-moving and often prefer interacting with their environment over prolonged handling. Rats are considered highly intelligent and are often described as “pocket puppies” due to their strong desire to bond with and seek attention from their owners. This means rats require more complex mental stimulation and regular out-of-cage time for interaction compared to the burrow-centric needs of the gerbil.