common nut clam vs Polar bear

Nucula nucleus compared with Ursus maritimus

Key Differences

common nut clam is Least Concern while Polar bear is Vulnerable.

Taxonomic Classification

Rank	common nut clam	Polar bear
Kingdom same	Animalia (動物)	Animalia (動物)
Phylum	Mollusca (軟体動物)	Chordata (脊索動物)
Class	Bivalvia (二枚貝)	Mammalia (哺乳類)
Order	Nuculida (Nuculida)	Carnivora (ネコ目)
Family	Nuculidae	Ursidae (Bears)
Genus	Nucula	Ursus (Bears)
Species	Nucula nucleus	Ursus maritimus

Evolutionary Relationship

common nut clam and Polar bear share a common ancestor at the Kingdom level: Animalia. (動物)

表示 Kingdom: Animalia

Conservation Status

common nut clam

LC — Least Concern

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	common nut clam	Polar bear
Diet	—	Carnivore
Average Lifespan	—	25 years
Average Length	—	2.4 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

common nut clam

Habitat

Native to Europe, inhabiting ecosystems characteristic of the region.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

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 nut clam

<em>Nucula nucleus</em>, the common nut clam, is a small marine bivalve mollusk in the family Nuculidae, among the most primitive living bivalves in terms of evolutionary lineage. This deposit-feeding species typically burrows into soft sediments — muddy and sandy substrates — in coastal and subtidal marine environments. <em>Nucula nucleus</em> uses its elongated palp proboscides to sort organic particles and detritus from sediment, making it a key functional contributor to benthic nutrient cycling. Its geographic range spans European Atlantic and Mediterranean coasts, with documented occurrences in Belgium, Denmark, Norway, and Sweden, typically in sheltered bays, estuaries, and sublittoral soft-bottom habitats. The species is currently assessed as Least Concern by the IUCN. Biological traits such as lifespan, body size, and diet remain poorly documented at a population level for this species in formal assessments, though it is known as a selective deposit feeder. The common nut clam plays an important role in benthic community structure and sediment processing, and serves as prey for demersal fish, sea stars, and other bottom-dwelling predators across its European range.

Polar bear

地球上で最大の陸上肉食動物であるホッキョクグマは700kgを超えることがあり、カナダからロシアまでの北極海氷域全体に分布する。ワモンアザラシとヒゲアザラシを狩るために海氷に依存する高度に特化した海洋哺乳類である。広大な距離を泳ぐことができる優れた泳者でもある。脆弱種に指定されており、気候変動による急激な北極海氷の消失で個体群が深刻な圧力を受けている。