Common Ink Cap vs Common Water Rat

Coprinopsis atramentaria compared with Hydromys chrysogaster

Taxonomic Classification

Rank	Common Ink Cap	Common Water Rat
Kingdom	Fungi (Fungi)	Animalia (Animals)
Phylum	Basidiomycota (Club Fungi)	Chordata (Chordates)
Class	Agaricomycetes (Mushrooms)	Mammalia (Mammals)
Order	Agaricales (Gilled Mushrooms)	Rodentia (Rodents)
Family	Psathyrellaceae	Muridae (Mice & Rats)
Genus	Coprinopsis	Hydromys
Species	Coprinopsis atramentaria	Hydromys chrysogaster

Conservation Status

Common Ink Cap

LC — Least Concern

Common Water Rat

LC — Least Concern

Physical Characteristics

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

Habitat & Geographic Range

Common Ink Cap

Habitat

Typically found in forest floors, decomposing wood, and soil ecosystems.

Range

Widely distributed across Asia (Taiwan), Europe (4 countries), and North America (United States).

Common Water Rat

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Common Ink Cap

<em>Coprinopsis atramentaria</em>, commonly known as the common ink cap, is a saprotrophic fungus in the family Psathyrellaceae. It is classified as Least Concern on the IUCN Red List, with a distribution spanning Asia (including Taiwan), Europe, and North America. The species typically grows on forest floors, buried wood, stumps, and other decomposing woody substrates in temperate regions. As a saprotroph, it plays an important ecological role in breaking down organic matter. The common ink cap is notable for containing coprine, a compound that inhibits aldehyde dehydrogenase and causes unpleasant reactions when consumed with alcohol. Diet information for this species is not available in current records. Biological traits of this species remain poorly documented in the scientific literature.

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.