common grey sea slug vs Common Moonwort

Aeolidia papillosa compared with Botrychium lunaria

Key Differences

• common grey sea slug is Least Concern while Common Moonwort is Endangered.

Taxonomic Classification

Rank	common grey sea slug	Common Moonwort
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Mollusca (Mollusks)	Tracheophyta
Class	Gastropoda (Gastropoda)	Polypodiopsida (Polypodiopsida)
Order	Nudibranchia (Nudibranchia)	Ophioglossales (Ophioglossales)
Family	Aeolidiidae	Ophioglossaceae
Genus	Aeolidia	Botrychium
Species	Aeolidia papillosa	Botrychium lunaria

Conservation Status

common grey sea slug

LC — Least Concern

Common Moonwort

EN — Endangered

Physical Characteristics

Attribute	common grey sea slug	Common Moonwort
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 Moonwort

Habitat

Typically found in moist, shaded forest floors and tropical canopies.

Range

Widely distributed across Asia (Taiwan), Europe (5 countries), and North America (United States). Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

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 Moonwort

Common Moonwort (<em>Botrychium lunaria</em>) is a small fern in the genus <em>Botrychium</em>, family Ophioglossaceae. It is distributed across Asia, Europe, and North America, with confirmed presence in Belgium, Denmark, Norway, Portugal, and Sweden, as well as Taiwan and the United States. The species is typically found in moist, shaded forest floors and tropical canopies. Common Moonwort is currently classified as Endangered on the IUCN Red List, indicating that it faces significant conservation challenges across its range. Its distinctive frond is divided into two parts: a sterile fan-shaped leaf portion with rounded lobes resembling a crescent moon, and a fertile spike bearing spore-bearing structures. As a fern ally rather than a flowering plant, it reproduces via spores rather than seeds. The species is associated with stable, undisturbed habitats including ancient grasslands, upland heaths, and rocky slopes. Its sensitivity to habitat disturbance and changes in land management are thought to contribute to population declines. Specific biological measurements such as lifespan and dimensions are not documented in available records.

Shared Countries

Both species can be found in 4 countries:

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