Common Seal vs Ray's Knotgrass

Phoca vitulina compared with Polygonum oxyspermum

Key Differences

• Common Seal is Near Threatened while Ray's Knotgrass is Endangered.

Taxonomic Classification

Rank	Common Seal	Ray's Knotgrass
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Chordata (Chordates)	Magnoliophyta (Flowering Plants)
Class	Mammalia (Mammals)	Magnoliopsida (Dicots)
Order	Pinnipedia (Seals & Sea Lions)	Caryophyllales (Caryophyllales)
Family	Phocidae (True Seals)	Polygonaceae
Genus	Phoca (Harbor Seals)	Polygonum
Species	Phoca vitulina	Polygonum oxyspermum

Conservation Status

Common Seal

NT — Near Threatened

Population: ~500.0K

Trend: Stable →

Ray's Knotgrass

EN — Endangered

Physical Characteristics

Attribute	Common Seal	Ray's Knotgrass
Diet	Carnivore	—
Average Lifespan	30 years	—
Average Length	1.7 m	—
Average Weight	80.0 kg	—

Habitat & Geographic Range

Common Seal

Habitat

Typically found in diverse ecosystems where prey species are available.

Range

Found across Europe (7 countries) and North America (United States). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Ray's Knotgrass

Habitat

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

Range

Distributed across Denmark, Norway, and Sweden. Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

Common Seal

The most widely distributed pinniped, harbor seals inhabit temperate and subarctic coastal waters of both the North Atlantic and North Pacific. Adults reach up to 130 kg and spend roughly equal time at sea hunting fish, squid, and crustaceans and hauling out on beaches or rocks to rest. Their large, expressive eyes are adapted for underwater vision in low light. Harbor seals are a critical food source for orcas, sharks, and polar bears.

Shared Countries

Both species can be found in 3 countries:

🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden