Chlorine Dust Lichen vs Polar bear

Chrysothrix chlorina compared with Ursus maritimus

Key Differences

Chlorine Dust Lichen is Extinct while Polar bear is Vulnerable.

Taxonomic Classification

Rank	Chlorine Dust Lichen	Polar bear
Kingdom	Fungi (真菌界)	Animalia (动物界)
Phylum	Ascomycota (子囊菌门)	Chordata (脊索动物门)
Class	Arthoniomycetes (星裂菌纲)	Mammalia (哺乳動物)
Order	Arthoniales (星裂菌目)	Carnivora (食肉目)
Family	Chrysotrichaceae	Ursidae (Bears)
Genus	Chrysothrix	Ursus (Bears)
Species	Chrysothrix chlorina	Ursus maritimus

Conservation Status

Chlorine Dust Lichen

EX — Extinct

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Chlorine Dust Lichen	Polar bear
Diet	—	Carnivore
Average Lifespan	—	25 years
Average Length	—	2.4 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

Chlorine Dust Lichen

Habitat

Native to Europe and North America and South America, inhabiting ecosystems characteristic of the region.

Range

Widely distributed across Europe (4 countries), North America (United States), 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.

Chlorine Dust Lichen

The Chlorine Dust Lichen (Chrysothrix chlorina) is a crustose lichen in the family Chrysotrichaceae, historically known from calcareous and siliceous rock surfaces and bark in parts of Europe, including the United Kingdom. It belongs to the genus Chrysothrix, a group of powdery, granular lichens that form bright yellow to greenish-yellow leprose thalli — lacking the organised cortex layers of most lichens — composed largely of granular soredia. Chrysothrix species produce unique secondary metabolites including rhizocarpic acid, which contributes to their intense yellow colouration and may serve as protection against grazing invertebrates. The Chlorine Dust Lichen takes its name from the sharp, bleach-like or chlorine odour emitted when the thallus is moistened — a distinctive diagnostic feature. The IUCN has assessed this species as Extinct in Great Britain, where it was historically recorded from ancient woodland and shaded rock sites but has not been confirmed in recent decades. Its apparent extinction in parts of its former range is attributed primarily to severe air quality degradation during the industrial era, as many crustose lichens are highly sensitive to sulphur dioxide and other atmospheric pollutants. It may persist in small areas of cleaner air, and improved air quality since deindustrialisation offers some hope for natural recolonisation.