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 (动物界)
Phylum	Magnoliophyta (木兰植物门)	Chordata (脊索动物门)
Class	Liliopsida (百合纲)	Mammalia (哺乳動物)
Order	Alismatales (泽泻目)	Carnivora (食肉目)
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.