Common Pill Woodlouse vs Polar bear

Armadillidium vulgare compared with Ursus maritimus

Key Differences

• Common Pill Woodlouse is Near Threatened while Polar bear is Vulnerable.

Taxonomic Classification

Rank	Common Pill Woodlouse	Polar bear
Kingdom same	Animalia (动物界)	Animalia (动物界)
Phylum	Arthropoda (节肢动物门)	Chordata (脊索动物门)
Class	Malacostraca (软甲纲)	Mammalia (哺乳動物)
Order	Isopoda (等足目)	Carnivora (食肉目)
Family	Armadillidiidae	Ursidae (Bears)
Genus	Armadillidium	Ursus (Bears)
Species	Armadillidium vulgare	Ursus maritimus

Evolutionary Relationship

Common Pill Woodlouse and Polar bear share a common ancestor at the Kingdom level: Animalia. (动物界)

Conservation Status

Common Pill Woodlouse

NT — Near Threatened

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Common Pill Woodlouse	Polar bear
Diet	—	Carnivore
Average Lifespan	—	25 years
Average Length	—	2.4 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

Common Pill Woodlouse

Habitat

Typically found in marine, freshwater, and terrestrial environments.

Range

Widely distributed across Africa (South Africa), Asia (Japan), Europe (6 countries), and North America (United States). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

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 Pill Woodlouse

<em>Armadillidium vulgare</em>, the common pill woodlouse, is a terrestrial isopod crustacean in the family Armadillidiidae, widely recognised for its ability to roll into a tight sphere when disturbed, a defensive behaviour that gives it the common name "pill bug" or "roly-poly." Unlike most crustaceans, it is fully adapted to life on land, breathing through modified gill-like structures that must remain moist. The species inhabits a broad range of environments, typically occurring under rocks, leaf litter, decaying wood, and in gardens and agricultural land, where it feeds on decomposing organic matter, playing an important role in nutrient cycling. <em>Armadillidium vulgare</em> is distributed across Europe, parts of Asia including Japan, South Africa, and North America including the United States, reflecting its success as a cosmopolitan species often transported inadvertently by human activity. It is assessed as Near Threatened on the IUCN Red List. Biological traits such as average lifespan, precise body dimensions, and detailed dietary composition across its range remain poorly documented in the scientific literature. Females brood their young in a marsupium, and the species is capable of parthenogenesis under certain conditions, contributing to reproductive flexibility.

Polar bear

北极熊是地球上最大的陆地食肉动物，体重可超过700千克，分布于从加拿大到俄罗斯的北极海冰区。是高度特化的海洋哺乳动物，依赖海冰捕猎环斑海豹和髯海豹。是优秀的游泳者，能够横渡广阔的开阔水域。被列为易危种，因气候变化导致北极海冰迅速减少，种群正受到严重威胁。

Shared Countries

Both species can be found in 1 countries:

🇳🇴 Norway