vs Common Water Rat

Chrysococcus cordiformis compared with Hydromys chrysogaster

Key Differences

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

Taxonomic Classification

Rank		Common Water Rat
Kingdom	Chromista (Chromista)	Animalia (Animals)
Phylum	Ochrophyta (Ochrophyta)	Chordata (Chordates)
Class	Chrysophyceae (Chrysophyceae)	Mammalia (Mammals)
Order	Chromulinales (Chromulinales)	Rodentia (Rodents)
Family	Dinobryaceae	Muridae (Mice & Rats)
Genus	Chrysococcus	Hydromys
Species	Chrysococcus cordiformis	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 Denmark, Norway, and Sweden.

Common Water Rat

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Chrysococcus cordiformis is a freshwater chrysophyte microalga in the genus Chrysococcus, class Chrysophyceae. The species epithet cordiformis — heart-shaped — describes the characteristic lorica shape of this species, a lorica being the rigid or semi-rigid outer case secreted by the cell that gives Chrysococcus its distinctive appearance. The heart-shaped lorica of C. cordiformis provides a clear morphological character distinguishing it from species with spherical, ovoid, or otherwise shaped loricas. Chrysococcus species are unicellular, loricate golden algae that inhabit freshwater ecosystems, particularly the euphotic zones of oligotrophic to mesotrophic lakes and ponds. C. cordiformis has been documented from Norwegian and Swedish freshwater environments, which provide cold, clear-water habitats typical of Scandinavian highland and boreal lakes. Records also extend to Brazil, indicating a wide geographic range consistent with the passive dispersal capacity of small, light-weight planktonic microalgae. The cells of C. cordiformis possess one or two flagella that protrude through an opening in the lorica, enabling active swimming in the water column. Photosynthesis is conducted using chlorophylls a and c with carotenoid accessory pigments. Chrysococcus species may also feed phagotrophically on bacteria. C. cordiformis has not been formally evaluated under IUCN criteria and retains a conservation status of Not Evaluated. It represents a characteristic member of freshwater chrysophyte communities associated with cool, acidic, or nutrient-poor Scandinavian lake systems.

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.