Big Finner vs common freshwater nerite

Balaenoptera physalus compared with Theodoxus fluviatilis

Key Differences

• Big Finner is Endangered while common freshwater nerite is Least Concern.

Taxonomic Classification

Rank	Big Finner	common freshwater nerite
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Chordata (Chordates)	Mollusca (Mollusks)
Class	Mammalia (Mammals)	Gastropoda (Gastropoda)
Order	Cetacea (Whales & Dolphins)	Cycloneritida (Cycloneritida)
Family	Balaenopteridae (Rorquals)	Neritidae
Genus	Balaenoptera (Rorquals)	Theodoxus
Species	Balaenoptera physalus	Theodoxus fluviatilis

Evolutionary Relationship

Big Finner and common freshwater nerite share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Big Finner

EN — Endangered

common freshwater nerite

LC — Least Concern

Physical Characteristics

Attribute	Big Finner	common freshwater nerite
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Big Finner

Habitat

Found across multiple habitat types including tropical and subtropical dry broadleaf forests, flooded grasslands and savannas, and montane grasslands and shrublands, among 4 distinct biome types within the Neotropic biogeographic realm.

Range

Widely distributed across Asia (Taiwan), Europe (5 countries), and South America (Colombia, Ecuador, Venezuela). Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

common freshwater nerite

Habitat

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

Range

Found across Europe (11 countries).

Big Finner

Big Finner (Balaenoptera physalus) is classified as Endangered (EN) on the IUCN Red List. At high risk of extinction in the wild, with significant population decline and ongoing threats to survival.

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.

Shared Countries

Both species can be found in 4 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden