ワラジムシ vs クマワラジムシ

Porcellio scaber compared with Porcellio laevis

Taxonomic Classification

Rank	ワラジムシ	クマワラジムシ
Kingdom same	Animalia (動物)	Animalia (動物)
Phylum same	Arthropoda (節足動物)	Arthropoda (節足動物)
Class same	Malacostraca (軟甲綱)	Malacostraca (軟甲綱)
Order same	Isopoda (ワラジムシ目)	Isopoda (ワラジムシ目)
Family same	Porcellionidae	Porcellionidae
Genus same	Porcellio	Porcellio
Species	Porcellio scaber	Porcellio laevis

Evolutionary Relationship

ワラジムシ and クマワラジムシ share a common ancestor at the Genus level: Porcellio.

Conservation Status

ワラジムシ

LC — Least Concern

クマワラジムシ

LC — Least Concern

Physical Characteristics

Attribute	ワラジムシ	クマワラジムシ
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

ワラジムシ

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and deserts and xeric shrublands within the Indomalayan biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

Widely distributed across Africa (South Africa), Asia (Japan, Sri Lanka), Europe (5 countries), North America (United States), and South America (Brazil).

クマワラジムシ

Habitat

Typically found in marine, freshwater, and terrestrial environments.

Range

Widely distributed across Africa (South Africa), Asia (Japan), Europe (12 countries), North America (United States), and South America (Brazil).

ワラジムシ

<em>Porcellio scaber</em>, the common rough woodlouse, is a terrestrial isopod crustacean in the family Porcellionidae. One of the most widespread and abundant woodlouse species in the world, it has established itself across Europe, the Americas, Asia, Australia, and numerous oceanic islands, including populations documented in Belgium, Brazil, Denmark, Japan, and Norway. This synanthropic species typically inhabits decaying leaf litter, rotting wood, compost heaps, under stones, and in the soil of gardens, forests, and human-modified landscapes. It thrives in moist, sheltered microhabitats and shows some tolerance for drier conditions compared to related species. As a detritivore, the common rough woodlouse feeds primarily on decaying organic matter including leaf litter, rotting wood, fungi, and plant debris, playing a significant role in nutrient cycling and decomposition processes. The species reproduces sexually, with females brooding eggs and juveniles in a specialized brood pouch. Assessed as Least Concern by the IUCN, its cosmopolitan distribution and high adaptability make it one of the most ecologically resilient terrestrial isopods. It is easily identified by its rough, grey to dark brown dorsal surface with pale lateral markings. Biological traits such as average lifespan and typical body length remain variable across populations and are not uniformly documented in standardized databases.

Shared Countries

Both species can be found in 9 countries:

🇧🇪 Belgium 🇧🇷 Brazil 🇩🇰 Denmark 🇯🇵 Japan 🇳🇴 Norway 🇵🇹 Portugal 🇿🇦 South Africa 🇸🇪 Sweden 🇺🇸 United States