blue whale vs common pygmy woodlouse

Balaenoptera musculus compared with Trichoniscus pusillus

Key Differences

• blue whale is Vulnerable while common pygmy woodlouse is Least Concern.

Taxonomic Classification

Rank	blue whale	common pygmy woodlouse
Kingdom same	Animalia (動物)	Animalia (動物)
Phylum	Chordata (脊索動物)	Arthropoda (節足動物)
Class	Mammalia (哺乳類)	Malacostraca (軟甲綱)
Order	Cetacea (Whales & Dolphins)	Isopoda (ワラジムシ目)
Family	Balaenopteridae (Rorquals)	Trichoniscidae
Genus	Balaenoptera (Rorquals)	Trichoniscus
Species	Balaenoptera musculus	Trichoniscus pusillus

Evolutionary Relationship

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

Conservation Status

blue whale

VU — Vulnerable

Population: ~15.0K

Trend: Increasing ↑

common pygmy woodlouse

LC — Least Concern

Physical Characteristics

Attribute	blue whale	common pygmy 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 pygmy woodlouse

Habitat

Typically found in marine, freshwater, and terrestrial environments.

Range

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

blue whale

地球上で生きたことが知られている最大の動物であるシロナガスクジラ（Balaenoptera musculus）は、体長33メートル、体重200トンに達することができ、心臓だけで小型自動車ほどの重さがあります。全ての海洋に生息し、極地の餌場と熱帯の繁殖地の間を回遊します。1日最大4トンのオキアミを摂取する濾過摂食者です。20世紀の捕鯨による絶滅危機からの回復後、世界的な個体数は10,000〜25,000頭と推定される絶滅危惧種です。

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.

Shared Countries

Both species can be found in 4 countries:

🇩🇰 Denmark 🇳🇴 Norway 🇵🇹 Portugal 🇸🇪 Sweden