common grey sea slug vs common river snail

Aeolidia papillosa compared with Viviparus viviparus

Taxonomic Classification

Rank	common grey sea slug	common river snail
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Mollusca (Mollusks)	Mollusca (Mollusks)
Class same	Gastropoda (Gastropoda)	Gastropoda (Gastropoda)
Order	Nudibranchia (Nudibranchia)	Architaenioglossa (Architaenioglossa)
Family	Aeolidiidae	Viviparidae
Genus	Aeolidia	Viviparus
Species	Aeolidia papillosa	Viviparus viviparus

Evolutionary Relationship

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

Conservation Status

common grey sea slug

LC — Least Concern

common river snail

LC — Least Concern

Physical Characteristics

Attribute	common grey sea slug	common river snail
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

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 river snail

Habitat

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

Range

Found across Europe (7 countries).

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.

common river snail

<em>Viviparus viviparus</em>, the common river snail, is a freshwater gastropod mollusk in the family Viviparidae, order Architaenioglossa. It is distributed across Europe, with populations documented in Austria, Belgium, Bulgaria, Czech Republic, France, Germany, and Hungary, among other countries, typically inhabiting slow-moving and still freshwater bodies including rivers, canals, ponds, and ditches. The species is assessed as Least Concern on the IUCN Red List. Common river snails typically live in soft-sediment benthic habitats, grazing on algae, aquatic plant material, and organic detritus using a radula — a ribbon-like feeding organ characteristic of gastropods. <em>Viviparus viviparus</em> is notable among freshwater mollusks for being viviparous, giving birth to fully formed juvenile snails rather than laying eggs, an adaptation reflected in both the genus and family names. This reproductive strategy typically results in small litter sizes but high juvenile survival compared to egg-laying mollusks. The species plays a role in benthic nutrient cycling and serves as prey for waterfowl, fish, and crayfish. Biological traits such as precise lifespan, body measurements, and population density data vary across localities and remain incompletely documented in comprehensive studies.

Shared Countries

Both species can be found in 4 countries:

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