A rat is a medium-sized, long-tailed rodent belonging to the family Muridae, the largest family within the order Rodentia. These mammals are found globally and are recognized by their characteristic physical makeup. The following features explain the typical appearance of a rat, focusing on dimensions, anatomy, and the differences between common species.
General Size and Body Structure
Rats are notably larger and heavier than many other common rodents. Adult rats typically measure between 9 to 11 inches in body length, excluding the tail. Adult males often weigh between 16 to 23 ounces. The overall body shape is robust, contributing to their stocky appearance. Their dense fur is often coarse and commonly colored brown, gray, or black, often with a lighter shade on the belly.
Distinguishing Features of the Head and Tail
The head features a snout that can be blunt or pointed, depending on the species. Rats have dark eyes that provide a wide field of vision but poor depth perception. The ears are relatively small and thick compared to the head size, and they are nearly bald. The tail is a primary identifier: it is long, thick, and characteristically scaly. Although often appearing hairless, it is covered in very short, fine hairs. This appendage is used for balance and thermoregulation, and its length relative to the body varies significantly between species.
Comparing Common Rat Species
The two most frequently encountered species are the Norway Rat (Rattus norvegicus), or brown rat, and the Roof Rat (Rattus rattus), or black rat. The Norway rat is the larger of the two, possessing a stocky, heavy body with a blunt nose. Its fur is typically coarse and brownish-gray, and its tail is shorter than its head and body combined. In contrast, the Roof rat has a more slender body built for climbing. It features a pointed snout and noticeably larger, thinner ears that can cover its eyes when pressed forward. This species is often black or dark brown, and its tail is longer than the length of its head and body put together.
Rat Versus Mouse Key Differences
The most obvious distinction between a rat and a common house mouse is their overall size. Adult rats are significantly larger; a mature house mouse typically measures only 3 to 4 inches in body length. A rat’s weight can be over a pound, whereas a mouse usually weighs less than an ounce. The head structure also differs markedly. Rats have a large head proportionate to their body and a blunt snout. Mice have a much smaller head and a triangular, pointed snout. A rat’s tail is thick, scaly, and hairless, while a mouse has a thinner tail covered in fine hair. Finally, a rat’s ears are small relative to its head, but a mouse possesses large ears disproportionate to its smaller head size.