vs Common Water Rat

Colacium sideropus compared with Hydromys chrysogaster

Key Differences

is Not Evaluated while Common Water Rat is Least Concern.

Taxonomic Classification

Rank		Common Water Rat
Kingdom	Protozoa (protozoa)	Animalia (Animals)
Phylum	Euglenozoa (Euglenozoa)	Chordata (Chordates)
Class	Euglenoidea (Euglenoidea)	Mammalia (Mammals)
Order	Euglenida (Euglenida)	Rodentia (Rodents)
Family	Euglenaceae	Muridae (Mice & Rats)
Genus	Colacium	Hydromys
Species	Colacium sideropus	Hydromys chrysogaster

Conservation Status

NE — Not Evaluated

Common Water Rat

LC — Least Concern

Physical Characteristics

Attribute		Common Water Rat
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Habitat

Native to Europe and South America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Brazil and Sweden.

Common Water Rat

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Colacium sideropus is a microscopic euglenoid protist belonging to the family Euglenaceae, characterized by its sessile, colonial lifestyle attaching to aquatic invertebrates and zooplankton. Members of the genus Colacium are distinguished from free-swimming euglenoids by their stalked or clustered growth form, anchoring to the bodies of crustaceans such as copepods and cladocerans in freshwater environments. Like other photosynthetic euglenoids, Colacium possesses chloroplasts derived from secondary endosymbiosis with a green alga, allowing it to perform photosynthesis under favorable light conditions. The relationship with host invertebrates is generally considered epibiotic rather than parasitic, with the protist colonizing the external surfaces of its host without causing significant harm. Colacium sideropus occurs in freshwater lakes, ponds, and slow-moving streams where its zooplankton hosts are abundant. Its ecological role includes contributing to microbial food webs and nutrient cycling within freshwater ecosystems. As with many microscopic protists, its true distribution and abundance are difficult to assess from macroscopic surveys, and it is likely globally distributed wherever suitable hosts exist in freshwater habitats.

Common Water Rat

<em>Hydromys chrysogaster</em>, commonly known as the common water rat or rakali, is a semi-aquatic rodent in the family Muridae, native to Australia and New Guinea. It is classified as Least Concern by the IUCN, reflecting its relatively stable population across a broad range of freshwater and estuarine habitats on the Australian continent and associated islands. The species typically inhabits the banks of rivers, lakes, wetlands, and estuaries, where it constructs burrows in streambanks. It is highly adapted for an aquatic lifestyle, with partially webbed hind feet, a flattened head, and a dense waterproof coat. <em>Hydromys chrysogaster</em> is a carnivore, typically feeding on fish, crustaceans, mussels, frogs, and aquatic invertebrates, which it often carries to elevated feeding platforms to consume. The species is nocturnal and crepuscular, most active during early morning and evening hours near the water's edge. Biological traits including average lifespan, body length, and weight remain poorly documented in standardized databases, though adults are generally robust for a rodent, reportedly reaching body lengths of 20–35 cm excluding the tail. Geographic range details for this particular record remain incompletely documented in available data sources. Ecologically, the common water rat is an important apex predator in small-scale freshwater food webs and serves as an indicator species for wetland health in Australian riparian systems.