common Atlantic octopus vs common grey sea slug

Octopus vulgaris compared with Aeolidia papillosa

Key Differences

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

Taxonomic Classification

Rank	common Atlantic octopus	common grey sea slug
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Mollusca (Mollusks)	Mollusca (Mollusks)
Class	Cephalopoda (Cephalopods)	Gastropoda (Gastropoda)
Order	Octopoda (Octopuses)	Nudibranchia (Nudibranchia)
Family	Octopodidae (Common Octopuses)	Aeolidiidae
Genus	Octopus (Octopuses)	Aeolidia
Species	Octopus vulgaris	Aeolidia papillosa

Evolutionary Relationship

common Atlantic octopus and common grey sea slug share a common ancestor at the Phylum level: Mollusca. (Mollusks)

Conservation Status

common Atlantic octopus

NE — Not Evaluated

Trend: Stable →

common grey sea slug

LC — Least Concern

Physical Characteristics

Attribute	common Atlantic octopus	common grey sea slug
Diet	Carnivore	—
Average Lifespan	2 years	—
Average Length	60 cm	—
Average Weight	5.0 kg	—

Habitat & Geographic Range

common Atlantic octopus

Habitat

Typically found in diverse ecosystems where prey species are available.

Range

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

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 Atlantic octopus

One of the most studied invertebrates in neuroscience and behavioral biology, common octopuses inhabit rocky reefs and seafloors in tropical and temperate coastal waters globally. Highly intelligent with distributed nervous systems — two-thirds of their 500 million neurons reside in their arms — they demonstrate tool use, problem-solving, and individual personalities. Masters of camouflage, they change skin color and texture in milliseconds. They have three hearts, blue copper-based blood, and extremely short lifespans of 1–2 years.

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:

🇨🇱 Chile 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden