common freshwater nerite vs Polar bear

Theodoxus fluviatilis compared with Ursus maritimus

Key Differences

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

Taxonomic Classification

Rank	common freshwater nerite	Polar bear
Kingdom same	Animalia (สัตว์)	Animalia (สัตว์)
Phylum	Mollusca (มอลลัสกา)	Chordata (สัตว์มีแกนสันหลัง)
Class	Gastropoda (ชั้นแกสโทรโพดา)	Mammalia (สัตว์เลี้ยงลูกด้วยน้ำนม)
Order	Cycloneritida (Cycloneritida)	Carnivora (สัตว์กินเนื้อ)
Family	Neritidae	Ursidae (Bears)
Genus	Theodoxus	Ursus (Bears)
Species	Theodoxus fluviatilis	Ursus maritimus

Evolutionary Relationship

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

Conservation Status

common freshwater nerite

LC — Least Concern

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	common freshwater nerite	Polar bear
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).

Polar bear

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.

Polar bear

The largest land carnivore on Earth, polar bears can exceed 700 kg and are found across Arctic sea ice from Canada to Russia. Highly specialized marine mammals that rely on sea ice to hunt ringed and bearded seals. Excellent swimmers capable of covering vast distances in open water. Listed as Vulnerable, with populations under severe pressure from rapid Arctic sea ice loss due to climate change.

Shared Countries

Both species can be found in 1 countries:

🇳🇴 Norway