Colonial tunicate vs common grey sea slug

Symplegma reptans compared with Aeolidia papillosa

Key Differences

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

Taxonomic Classification

Rank	Colonial tunicate	common grey sea slug
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Chordata (Chordates)	Mollusca (Mollusks)
Class	Ascidiacea (Ascidiacea)	Gastropoda (Gastropoda)
Order	Stolidobranchia (Stolidobranchia)	Nudibranchia (Nudibranchia)
Family	Styelidae	Aeolidiidae
Genus	Symplegma	Aeolidia
Species	Symplegma reptans	Aeolidia papillosa

Evolutionary Relationship

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

Conservation Status

Colonial tunicate

NE — Not Evaluated

common grey sea slug

LC — Least Concern

Physical Characteristics

Attribute	Colonial tunicate	common grey sea slug
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Colonial tunicate

Habitat

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

Range

Distributed across Mexico, 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.

Colonial tunicate

<em>Symplegma reptans</em> is a colonial tunicate in the family Styelidae with known occurrences in Mexico, Norway, Sweden, and the United States. This species has not been evaluated by the IUCN. Colonial tunicates in the genus <em>Symplegma</em> form encrusting sheet-like colonies on hard marine substrates, including rocks, shells, and artificial structures, in shallow coastal environments. Each colony is composed of multiple filter-feeding zooids embedded in a common tunic, through which nutrients and metabolites are distributed. The presence of <em>Symplegma reptans</em> across both the North Atlantic and Pacific coastal regions suggests either a wide native distribution or a history of introduction through maritime vectors such as ballast water and hull fouling. As a sessile filter feeder, this species contributes to water column filtration and nutrient cycling within benthic communities. The reproductive biology of <em>Symplegma reptans</em> likely involves both sexual reproduction via larval dispersal and asexual proliferation through budding within established colonies. 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 2 countries:

🇳🇴 Norway 🇸🇪 Sweden