common freshwater nerite vs Red-billed Duck

Theodoxus fluviatilis compared with Anas erythrorhyncha

Taxonomic Classification

Rank	common freshwater nerite	Red-billed Duck
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Mollusca (Mollusks)	Chordata (Chordates)
Class	Gastropoda (Gastropoda)	Aves (Birds)
Order	Cycloneritida (Cycloneritida)	Anseriformes (Anseriformes)
Family	Neritidae	Anatidae
Genus	Theodoxus	Anas
Species	Theodoxus fluviatilis	Anas erythrorhyncha

Evolutionary Relationship

common freshwater nerite and Red-billed Duck share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

common freshwater nerite

LC — Least Concern

Red-billed Duck

LC — Least Concern

Physical Characteristics

Attribute	common freshwater nerite	Red-billed Duck
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

common freshwater nerite

Habitat

Typically found in terrestrial and aquatic habitats including forests and freshwater.

Range

Found across Europe (11 countries).

Red-billed Duck

Habitat

Typically found in various aerial, terrestrial, and aquatic environments.

Range

Found across Europe (6 countries) and South America (Ecuador).

common freshwater nerite

<em>Theodoxus fluviatilis</em>, commonly known as the common freshwater nerite, is a small aquatic gastropod mollusc belonging to the family Neritidae. This species is widely distributed across Europe, with documented occurrences in Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Hungary, Latvia, Norway, and Sweden. It typically inhabits freshwater environments, including rivers, streams, and lakes, where it grazes on algae and biofilm on hard substrates such as rocks and submerged wood. The common freshwater nerite is assessed as Least Concern on conservation metrics, reflecting its broad distribution and relatively stable populations across much of its European range. Biological traits of this species remain poorly documented in the scientific literature. <em>Theodoxus fluviatilis</em> plays an ecological role as a grazer in freshwater benthic communities, contributing to the regulation of algal growth on hard surfaces. The species typically favors clean, well-oxygenated waters and can serve as an indicator of water quality in freshwater systems. Its distinctive small, dome-shaped shell with variable patterning makes it recognizable among freshwater invertebrates.

Red-billed Duck

Red-billed Duck (Anas erythrorhyncha) is classified as Least Concern (LC) on the IUCN Red List. Widespread and abundant across its range, with stable populations and no immediate conservation concerns.

Shared Countries

Both species can be found in 3 countries:

🇧🇪 Belgium 🇳🇴 Norway 🇬🇧 United Kingdom