Common Pill Woodlouse vs Oso Polar

Armadillidium vulgare compared with Ursus maritimus

Key Differences

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

Taxonomic Classification

Rank	Common Pill Woodlouse	Oso Polar
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Arthropoda (artrópodos)	Chordata (cordados)
Class	Malacostraca (Crustaceans)	Mammalia (mamíferos)
Order	Isopoda (Isopoda)	Carnivora (carnívoros)
Family	Armadillidiidae	Ursidae (Bears)
Genus	Armadillidium	Ursus (Bears)
Species	Armadillidium vulgare	Ursus maritimus

Evolutionary Relationship

Common Pill Woodlouse and Oso Polar share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Common Pill Woodlouse

NT — Near Threatened

Oso Polar

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Common Pill Woodlouse	Oso Polar
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.

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 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.

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