vs Common Water Rat

Chroococcus planctonicus compared with Hydromys chrysogaster

Key Differences

• is Not Evaluated while Common Water Rat is Least Concern.

Taxonomic Classification

Rank		Common Water Rat
Kingdom	Bacteria (Bacteria)	Animalia (Animals)
Phylum	Cyanobacteria (Cyanobacteria)	Chordata (Chordates)
Class	Cyanobacteriia	Mammalia (Mammals)
Order	Cyanobacteriales	Rodentia (Rodents)
Family	Microcystaceae	Muridae (Mice & Rats)
Genus	Chroococcus	Hydromys
Species	Chroococcus planctonicus	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, inhabiting ecosystems characteristic of the region.

Range

Distributed across Norway and Sweden.

Common Water Rat

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Chroococcus planctonicus is a species of cyanobacteria in the family Chroococcaceae, adapted to the planktonic lifestyle suggested by its specific epithet. Unlike some Chroococcus species that are primarily benthic or periphytic — attached to substrates — Chroococcus planctonicus is characteristic of open-water plankton communities in freshwater lakes and ponds. Planktonic cyanobacteria must maintain a position in the water column for optimal light exposure, and some have evolved gas vesicles to regulate buoyancy, though these are more developed in filamentous bloom-forming genera. Chroococcus planctonicus cells are spherical, occurring in pairs or tetrads within gelatinous sheaths, following the basic morphological plan of the genus. It has been documented from European freshwater systems including Swedish and Finnish lakes, where it contributes to the seasonal phytoplankton community. Cyanobacteria are important primary producers in freshwater ecosystems, particularly in summer when warm temperatures and stratified water columns favor their growth. However, Chroococcus planctonicus is not generally associated with harmful algal blooms, which are more characteristic of genera such as Microcystis and Anabaena. Its conservation status has not been assessed.

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.