Capped Orb Mussel vs common grey sea slug

Musculium lacustre compared with Aeolidia papillosa

Taxonomic Classification

Rank	Capped Orb Mussel	common grey sea slug
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Mollusca (Mollusks)	Mollusca (Mollusks)
Class	Bivalvia (Bivalvia)	Gastropoda (Gastropoda)
Order	Sphaeriida (Sphaeriida)	Nudibranchia (Nudibranchia)
Family	Sphaeriidae	Aeolidiidae
Genus	Musculium	Aeolidia
Species	Musculium lacustre	Aeolidia papillosa

Evolutionary Relationship

Capped Orb Mussel and common grey sea slug share a common ancestor at the Phylum level: Mollusca. (Mollusks)

Conservation Status

Capped Orb Mussel

LC — Least Concern

common grey sea slug

LC — Least Concern

Physical Characteristics

Attribute	Capped Orb Mussel	common grey sea slug
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Capped Orb Mussel

Habitat

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

Range

Distributed across 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.

Capped Orb Mussel

The Capped Orb Mussel (Musculium lacustre) is a species in the genus Musculium. It is currently classified as Least Concern (LC) on the IUCN Red List. Native to Europe and North America, inhabiting ecosystems characteristic of the region.

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 3 countries:

🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden