blue whale vs Common Rough Woodlouse

Balaenoptera musculus compared with Porcellio scaber

Key Differences

blue whale is Vulnerable while Common Rough Woodlouse is Least Concern.

Taxonomic Classification

Rank	blue whale	Common Rough Woodlouse
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Chordata (Chordates)	Arthropoda (Arthropods)
Class	Mammalia (Mammals)	Malacostraca (Crustaceans)
Order	Cetacea (Whales & Dolphins)	Isopoda (Isopoda)
Family	Balaenopteridae (Rorquals)	Porcellionidae
Genus	Balaenoptera (Rorquals)	Porcellio
Species	Balaenoptera musculus	Porcellio scaber

Evolutionary Relationship

blue whale and Common Rough Woodlouse share a common ancestor at the Kingdom level: Animalia. (Animals)

View Kingdom: Animalia

Conservation Status

blue whale

VU — Vulnerable

Population: ~15.0K

Trend: Increasing ↑

Common Rough Woodlouse

LC — Least Concern

Physical Characteristics

Attribute	blue whale	Common Rough Woodlouse
Diet	Carnivore	—
Average Lifespan	90 years	—
Average Length	30.0 m	—
Average Weight	150.0 t	—

Habitat & Geographic Range

blue whale

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and tropical and subtropical grasslands and savannas, among 11 distinct biome types. Populations are also found in montane and highland environments at higher elevations.

Range

Widely distributed across Asia (Taiwan), Europe (4 countries), and South America (Colombia, Ecuador). Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Common Rough Woodlouse

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).

blue whale

The largest animal ever known to have lived on Earth, blue whales can reach 33 meters and 200 tonnes — their hearts alone weigh as much as a small car. Found in all oceans, they migrate between polar feeding grounds and tropical breeding areas. Filter feeders consuming up to 4 tonnes of krill daily. Endangered, with global populations estimated at 10,000–25,000 after near-extinction from 20th-century whaling.

Common Rough Woodlouse

<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.