Common Water-Nymph vs Polar bear

Najas guadalupensis compared with Ursus maritimus

Key Differences

Common Water-Nymph is Not Evaluated while Polar bear is Vulnerable.

Taxonomic Classification

Rank	Common Water-Nymph	Polar bear
Kingdom	Plantae (植物)	Animalia (動物)
Phylum	Magnoliophyta (被子植物門)	Chordata (脊索動物)
Class	Liliopsida (単子葉植物綱)	Mammalia (哺乳類)
Order	Alismatales (オモダカ目)	Carnivora (ネコ目)
Family	Hydrocharitaceae	Ursidae (Bears)
Genus	Najas	Ursus (Bears)
Species	Najas guadalupensis	Ursus maritimus

Conservation Status

Common Water-Nymph

NE — Not Evaluated

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Common Water-Nymph	Polar bear
Diet	—	Carnivore
Average Lifespan	—	25 years
Average Length	—	2.4 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

Common Water-Nymph

Habitat

Typically found in grasslands, wetlands, forests, and cultivated landscapes.

Range

Widely distributed across Asia (Israel, Taiwan), Europe (4 countries), North America (4 countries), and South America (Brazil, Colombia).

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.

Common Water-Nymph

<em>Najas guadalupensis</em>, commonly known as the common water nymph or southern naiad, is a submerged aquatic plant in the family Hydrocharitaceae. Its conservation status is listed as Not Evaluated by the IUCN. The species has an extensive distribution spanning Asia, Europe, and the Americas, where it inhabits a wide range of lentic and lotic freshwater environments including ponds, lakes, slow streams, and irrigation channels. It typically grows fully submerged, rooting in sandy or muddy substrates in water ranging from shallow margins to depths exceeding two meters. The plant is slender and branching, with narrow, finely toothed leaves arranged oppositely or in whorls along the stem. <em>Najas guadalupensis</em> is adapted to a range of water quality conditions and can persist in turbid, nutrient-enriched environments where other aquatic macrophytes cannot. It typically reproduces through both seed and fragmentation, with stem fragments readily establishing new colonies. Pollination occurs underwater, with pollen dispersed directly through the water column. Biological traits including average lifespan, stem length, and mass remain poorly documented in standardized databases. Ecologically, common water nymph provides important submerged habitat structure for fish, invertebrates, and waterfowl, offering spawning substrate, foraging areas, and refuge from predators in the diverse freshwater systems it occupies throughout its broad geographic 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。