How do rats appear? - briefly
Rats are born after a gestation of roughly three weeks, producing litters of five to twelve offspring that develop fur and open their eyes within a few weeks, making them visible shortly after birth.
How do rats appear? - in detail
Rats are medium‑sized rodents with a body length of 15–20 cm, a tail roughly equal to or slightly longer than the torso, and a weight ranging from 150 g to 500 g depending on species and environment. Their skull is robust, featuring a pronounced occipital plate and large auditory bullae that enhance hearing. The dental formula is 1/1, 0/0, 0/0, 3/3, indicating a single pair of incisors in each jaw that grow continuously and are self‑sharpening through gnawing.
The fur covering the dorsal surface varies from dark brown to black, while the ventral side is typically lighter—gray, beige, or white. Seasonal molting can produce a temporary lighter coat in winter. The tail is hairless, sparsely covered with scales, and exhibits a slight taper toward the tip. Hind feet are larger than forefeet, equipped with elongated digits and a plantar pad that provides grip on vertical surfaces.
Sensory organs are highly developed. Eyes are relatively small, offering limited visual acuity but a wide field of view. Ears are large, mobile, and capable of detecting frequencies up to 80 kHz. Whiskers (vibrissae) extend from the snout and cheeks, serving as tactile sensors for navigating tight spaces.
Internally, the digestive system is adapted for omnivorous diets, with a large cecum that ferments plant material. The respiratory system includes a high‑capacity diaphragm, supporting sustained activity. Muscular structure emphasizes strong forelimb flexors for gnawing and powerful hindlimb extensors for rapid sprinting and climbing.
Key characteristics can be summarized:
- Body size: 15–20 cm (head‑body), tail 15–25 cm
- Weight: 150–500 g
- Dorsal pelage: dark brown to black; ventral pelage: lighter shades
- Tail: hairless, scaly, slightly tapered
- Skull: robust, large auditory bullae, ever‑growing incisors
- Sensory organs: small eyes, large mobile ears, extensive whisker array
- Limb morphology: enlarged hind feet, strong forelimb muscles
These traits collectively define the physical appearance of rats across common species such as the brown rat (Rattus norvegicus) and the black rat (Rattus rattus).