common freshwater nerite vs Oso Polar

Theodoxus fluviatilis compared with Ursus maritimus

Key Differences

• common freshwater nerite is Least Concern while Oso Polar is Vulnerable.

Taxonomic Classification

Rank	common freshwater nerite	Oso Polar
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Mollusca (moluscos)	Chordata (cordados)
Class	Gastropoda (gastrópodos)	Mammalia (mamíferos)
Order	Cycloneritida (Cycloneritida)	Carnivora (carnívoros)
Family	Neritidae	Ursidae (Bears)
Genus	Theodoxus	Ursus (Bears)
Species	Theodoxus fluviatilis	Ursus maritimus

Evolutionary Relationship

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

Conservation Status

common freshwater nerite

LC — Least Concern

Oso Polar

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	common freshwater nerite	Oso Polar
Diet	—	Carnivore
Average Lifespan	—	25 years
Average Length	—	2.4 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

common freshwater nerite

Habitat

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

Range

Found across Europe (11 countries).

Oso Polar

Habitat

Found across multiple habitat types including temperate broadleaf and mixed forests, temperate coniferous forests, and boreal forests and taiga, among 4 distinct biome types within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

Found in Norway. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

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.

Oso Polar

El mayor carnivoro terrestre de la Tierra, el oso polar puede superar los 700 kg y se encuentra en el hielo marino del Artico, desde Canada hasta Rusia. Es un mamifero marino altamente especializado que depende del hielo marino para cazar focas anilladas y barbadas. Excelente nadador capaz de cubrir grandes distancias en agua abierta. Clasificado como Vulnerable, sus poblaciones soportan una presion severa por la rapida perdida de hielo marino artico debida al cambio climatico.

Shared Countries

Both species can be found in 1 countries:

🇳🇴 Norway