Common Bithynia vs common grey sea slug

Bithynia tentaculata compared with Aeolidia papillosa

Taxonomic Classification

Rank	Common Bithynia	common grey sea slug
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Mollusca (Mollusks)	Mollusca (Mollusks)
Class same	Gastropoda (Gastropoda)	Gastropoda (Gastropoda)
Order	Littorinimorpha (Littorinimorpha)	Nudibranchia (Nudibranchia)
Family	Bithyniidae	Aeolidiidae
Genus	Bithynia	Aeolidia
Species	Bithynia tentaculata	Aeolidia papillosa

Evolutionary Relationship

Common Bithynia and common grey sea slug share a common ancestor at the Class level: Gastropoda. (Gastropoda)

Conservation Status

Common Bithynia

LC — Least Concern

common grey sea slug

LC — Least Concern

Physical Characteristics

Attribute	Common Bithynia	common grey sea slug
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Common Bithynia

Habitat

Typically found in terrestrial and aquatic habitats including forests and freshwater.

Range

Distributed across Belgium, Denmark, Norway, Sweden, and United States.

common grey sea slug

Habitat

Typically found in terrestrial and aquatic habitats including forests and freshwater.

Range

Distributed across Belgium, Chile, Denmark, Norway, and Sweden.

Common Bithynia

The common bithynia (<em>Bithynia tentaculata</em>) is a freshwater gastropod snail belonging to the family Bithyniidae. It is classified as Least Concern on the IUCN Red List and has been recorded across terrestrial and aquatic habitats in Belgium, Denmark, Norway, Sweden, and the United States. <em>Bithynia tentaculata</em> typically inhabits slow-moving or still freshwater environments such as lakes, ponds, canals, and rivers, often on muddy or sandy substrates where organic material is abundant. The species has a distinctive operculum that seals the shell opening, providing protection against desiccation and predators. It typically feeds by grazing on algae, detritus, and biofilms on submerged surfaces. The common bithynia serves as an intermediate host for several trematode parasites, making it ecologically significant in freshwater food webs and parasite life cycles. Biological traits of this species remain poorly documented in the scientific literature.

common grey sea slug

<em>Aeolidia papillosa</em>, commonly known as the common grey sea slug, is a nudibranch mollusc belonging to the genus Aeolidia within the family Aeolidiidae. Despite the species name referencing terrestrial and aquatic habitats including forests and freshwater, <em>Aeolidia papillosa</em> is primarily a marine organism. Its range includes Belgium, Chile, Denmark, Norway, and Sweden, indicating a distribution across the North Atlantic and into South American waters. Common grey sea slug is assessed as Least Concern on the IUCN Red List. The species is typically found in intertidal and subtidal zones, where it preys on sea anemones and stores stinging cells from its prey in its dorsal cerata for defense. Biological traits of this species remain poorly documented in the scientific literature.

Shared Countries

Both species can be found in 4 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden