What animal is a water rat? - briefly
The water rat, known as the rakali, is a semi‑aquatic rodent (Hydromys chrysogaster) native to Australia and New Guinea.
What animal is a water rat? - in detail
The term “water rat” refers to the semiaquatic rodent Hydromys chrysogaster, commonly called the rakali. It belongs to the family Muridae and the order Rodentia. The species is native to Australia and the southern coast of New Guinea, where it occupies freshwater lakes, rivers, swamps, and coastal mangroves.
Physical characteristics include a streamlined body, dense waterproof fur, and partially webbed hind feet. The tail is long, thick, and covered with scales that aid in swimming. Adults typically weigh 300–500 g and measure 30–45 cm in head‑body length, with the tail adding another 30–45 cm.
Key aspects of its biology:
- Habitat: Freshwater and brackish environments; nests built in burrows near water or in riverbanks.
- Diet: Opportunistic omnivore; consumes fish, crustaceans, insects, amphibians, eggs, and plant material.
- Behavior: Nocturnal; excellent swimmer; can remain submerged for up to two minutes; uses whiskers and keen hearing to locate prey underwater.
- Reproduction: Breeding occurs year‑round in warmer regions; litters contain 2–4 young; gestation lasts about 30 days; offspring are weaned after three weeks.
- Conservation status: Classified as Least Concern by the IUCN; populations are stable, though localized threats include habitat degradation, water pollution, and introduced predators such as feral cats.
Adaptations that enable an aquatic lifestyle include a flattened skull, nostrils that can close while submerged, and a high concentration of melanin in the skin, which reduces UV damage in open water. The water rat’s role as a predator of aquatic invertebrates helps regulate those populations, contributing to ecosystem balance.
Overall, the rakali represents a distinct evolutionary line among rodents, combining terrestrial and aquatic traits to thrive in diverse freshwater habitats across its range.