Common Earthball vs Common Water Rat

Scleroderma citrinum compared with Hydromys chrysogaster

Taxonomic Classification

Rank	Common Earthball	Common Water Rat
Kingdom	Fungi (Fungi)	Animalia (Animals)
Phylum	Basidiomycota (Club Fungi)	Chordata (Chordates)
Class	Agaricomycetes (Mushrooms)	Mammalia (Mammals)
Order	Boletales (Boletales)	Rodentia (Rodents)
Family	Sclerodermataceae	Muridae (Mice & Rats)
Genus	Scleroderma	Hydromys
Species	Scleroderma citrinum	Hydromys chrysogaster

Conservation Status

Common Earthball

LC — Least Concern

Common Water Rat

LC — Least Concern

Physical Characteristics

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

Habitat & Geographic Range

Common Earthball

Habitat

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

Range

Widely distributed across Asia (Taiwan), Europe (5 countries), North America (United States), and South America (Brazil, Chile).

Common Water Rat

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Common Earthball

<em>Scleroderma citrinum</em>, commonly known as the common earthball or pigskin poison puffball, is a widespread ectomycorrhizal fungus in the family Sclerodermataceae, classified as Least Concern by the IUCN. The species occurs across Asia, Europe, North America, and South America, typically found on forest floors, decomposing wood, and mineral-rich acidic soils in association with hardwood and conifer tree roots. Unlike true puffballs, <em>Scleroderma citrinum</em> is considered poisonous and should not be confused with edible species. Its thick, warty outer skin ranges from yellowish-brown to ochre and encloses a dark purplish-black spore mass that matures over time. The species plays an important ecological role as a mycorrhizal partner, forming mutualistic associations with the roots of oaks, beeches, pines, and other trees, facilitating the uptake of water and nutrients by host plants in exchange for photosynthetically derived carbon. Fruiting bodies typically emerge from late summer through autumn, releasing spores through irregular cracks or a central apical opening when mature. <em>Scleroderma citrinum</em> is a host for the parasitic fungus <em>Pseudoboletus parasiticus</em>, making it ecologically significant within forest fungal communities. 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.