common pygmy woodlouse vs Polar bear

Trichoniscus pusillus compared with Ursus maritimus

Key Differences

common pygmy woodlouse is Least Concern while Polar bear is Vulnerable.

Taxonomic Classification

Rank	common pygmy woodlouse	Polar bear
Kingdom same	Animalia (動物)	Animalia (動物)
Phylum	Arthropoda (節足動物)	Chordata (脊索動物)
Class	Malacostraca (軟甲綱)	Mammalia (哺乳類)
Order	Isopoda (ワラジムシ目)	Carnivora (ネコ目)
Family	Trichoniscidae	Ursidae (Bears)
Genus	Trichoniscus	Ursus (Bears)
Species	Trichoniscus pusillus	Ursus maritimus

Evolutionary Relationship

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

表示 Kingdom: Animalia

Conservation Status

common pygmy woodlouse

LC — Least Concern

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

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

Habitat & Geographic Range

common pygmy woodlouse

Habitat

Typically found in marine, freshwater, and terrestrial environments.

Range

Distributed across Denmark, Norway, Portugal, Sweden, and United States.

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 pygmy woodlouse

The Common Pygmy Woodlouse, <em>Trichoniscus pusillus</em>, is a small terrestrial isopod crustacean in the family Trichoniscidae, widely distributed across Europe and introduced to North America, with records from Denmark, Norway, Portugal, Sweden, and the United States. It is one of the most abundant and widespread woodlice in temperate regions, typically found in moist, dark microhabitats including under stones, logs, leaf litter, bark, and in soil crevices in gardens, woodlands, and grasslands. <em>Trichoniscus pusillus</em> is a very small species, measuring only a few millimeters in length, with a reddish-brown to pale pink coloration and a smooth, slightly convex body. Unlike many larger woodlice, it does not roll into a ball when disturbed. The species plays an important role in decomposition and nutrient cycling, fragmenting decaying plant material and facilitating microbial breakdown. It is parthenogenetic in many parts of its range, with all-female populations reproducing without males. The species is assessed as Least Concern on the IUCN Red List given its abundance and widespread distribution. Biological traits such as average lifespan, body size, and specific dietary preferences remain poorly documented for this species.

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。