Cobweb House-leek vs Polar bear

Sempervivum arachnoideum compared with Ursus maritimus

Key Differences

Cobweb House-leek is Not Evaluated while Polar bear is Vulnerable.

Taxonomic Classification

Rank	Cobweb House-leek	Polar bear
Kingdom	Plantae (植物)	Animalia (動物)
Phylum	Magnoliophyta (被子植物門)	Chordata (脊索動物)
Class	Magnoliopsida (モクレン綱)	Mammalia (哺乳類)
Order	Saxifragales (ユキノシタ目)	Carnivora (ネコ目)
Family	Crassulaceae	Ursidae (Bears)
Genus	Sempervivum	Ursus (Bears)
Species	Sempervivum arachnoideum	Ursus maritimus

Conservation Status

Cobweb House-leek

NE — Not Evaluated

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Cobweb House-leek	Polar bear
Diet	—	Carnivore
Average Lifespan	—	25 years
Average Length	—	2.4 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

Cobweb House-leek

Habitat

Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

Range

Found across Asia (Taiwan) and Europe (7 countries).

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.

Cobweb House-leek

The cobweb house-leek (Sempervivum arachnoideum) is a distinctive succulent plant in the family Crassulaceae, immediately recognizable by the dense network of white, cobweb-like hairs connecting the tips of its rosette leaves—an adaptation that may protect the plant from intense ultraviolet radiation, desiccation, and grazing at high altitudes. Native to the mountain ranges of Europe, including the Alps, Apennines, Carpathians, and Pyrenees, this species colonizes exposed rocky outcrops, cliff faces, scree slopes, and thin soils from subalpine to alpine elevations, often growing in large mats. The rosettes are small, typically 1–3 centimeters in diameter, composed of densely packed, fleshy leaves colored green with reddish or purplish tips. Like all sempervivums, S. arachnoideum is monocarpic at the rosette level—individual rosettes flower once, producing a stalk bearing clusters of pink to magenta star-shaped flowers before dying, while the plant persists through the continuous production of offsets that form spreading clonal colonies. The specific epithet 'arachnoideum' derives from the Latin for spider, referencing the cobweb-like pubescence. This species has been widely cultivated in rock gardens and alpine gardens worldwide for its ornamental appeal and extreme hardiness. Several varieties and cultivars exist, showing variation in hair density and leaf coloration. Its conservation status has not been formally evaluated by the IUCN, though it remains common throughout its native range.

Polar bear

地球上で最大の陸上肉食動物であるホッキョクグマは700kgを超えることがあり、カナダからロシアまでの北極海氷域全体に分布する。ワモンアザラシとヒゲアザラシを狩るために海氷に依存する高度に特化した海洋哺乳類である。広大な距離を泳ぐことができる優れた泳者でもある。脆弱種に指定されており、気候変動による急激な北極海氷の消失で個体群が深刻な圧力を受けている。