What are rats that live in water called? - briefly
Semi‑aquatic rodents are commonly called water rats; examples include the South American Nectomys species and the Australian rakali (Hydromys chrysogaster).
What are rats that live in water called? - in detail
The common name for semi‑aquatic rodents that spend most of their lives in water is water rat. This label applies to several unrelated species that share adaptations for swimming and foraging in wet environments.
Among the most frequently cited taxa are:
- Nectomys (South‑American water rats) – inhabit forest streams and floodplains in the Amazon basin.
- Arvicola (European water vole, sometimes called water rat) – found along rivers and marshes throughout Europe and western Asia.
- Hydromys (Australian water rat) – occupies coastal mangroves, freshwater lakes and creeks of Australia and New Zealand.
- Colomys (African water rat) – lives in the rainforests and swamps of West and Central Africa.
These rodents display convergent traits that facilitate an aquatic lifestyle. Fur is dense and water‑repellent, reducing heat loss. Hind feet are partially webbed, and many species possess a laterally flattened tail that functions as a rudder. Prominent whiskers and a keen sense of smell aid in detecting prey beneath the surface. Vision is generally adapted for low‑light conditions, reflecting their predominantly nocturnal activity patterns.
Habitat preferences include riverbanks, marshes, mangrove thickets, and the margins of ponds and lakes. They construct burrows or nests in riverbanks, often lining them with vegetation to maintain moisture. Diets are omnivorous: insects, crustaceans, small fish, amphibians, and aquatic plants constitute the bulk of intake, with occasional consumption of seeds and fruits found near water.
Reproductive cycles vary by region but typically involve multiple litters per year, each comprising two to six altricial young. Offspring are raised in sheltered burrows until they acquire swimming competence, after which they disperse to explore adjacent water bodies.
It is essential to distinguish water rats from the muskrat (Ondatra zibethicus). Although muskrats are often colloquially termed “rats,” they belong to a separate genus and family and exhibit distinct morphological and ecological characteristics. Likewise, beavers (Castor spp.) are larger, belong to the family Castoridae, and build dams—behaviors not shared by water rats.
In summary, the term “water rat” encompasses a diverse set of rodent species across multiple continents, unified by morphological adaptations for an amphibious existence, a preference for riparian habitats, and an omnivorous diet that exploits both aquatic and terrestrial resources.