common grey sea slug vs common hydra

Aeolidia papillosa compared with Hydra vulgaris

Key Differences

• common grey sea slug is Least Concern while common hydra is Not Evaluated.

Taxonomic Classification

Rank	common grey sea slug	common hydra
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Mollusca (Mollusks)	Cnidaria (Cnidarians)
Class	Gastropoda (Gastropoda)	Hydrozoa (Hydrozoa)
Order	Nudibranchia (Nudibranchia)	Anthoathecata (Anthoathecata)
Family	Aeolidiidae	Hydridae
Genus	Aeolidia	Hydra
Species	Aeolidia papillosa	Hydra vulgaris

Evolutionary Relationship

common grey sea slug and common hydra share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

common grey sea slug

LC — Least Concern

common hydra

NE — Not Evaluated

Physical Characteristics

Attribute	common grey sea slug	common hydra
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 hydra

Habitat

Native to Europe, inhabiting ecosystems characteristic of the region.

Range

Distributed across Denmark, Norway, and Sweden.

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 hydra

<em>Hydra vulgaris</em>, commonly known as the common hydra, is a small freshwater cnidarian in the family Hydridae. Its conservation status has not been formally evaluated by the IUCN. The species is recorded from Denmark, Norway, and Sweden, with its native range understood to encompass Europe broadly. It typically inhabits slow-moving or still freshwater bodies such as ponds, lakes, and streams, where it attaches to aquatic vegetation or submerged substrates. The common hydra is notable for its remarkable regenerative capabilities and has been the subject of substantial biological research. Diet information for this species is not available in current records. 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