Brook-Side Alder vs common door snail

Alnus serrulata compared with Clausilia bidentata

Taxonomic Classification

Rank	Brook-Side Alder	common door snail
Kingdom	Plantae (Plants)	Animalia (Animals)
Phylum	Magnoliophyta (Flowering Plants)	Mollusca (Mollusks)
Class	Magnoliopsida (Dicots)	Gastropoda (Gastropoda)
Order	Fagales (Beeches & Oaks)	Stylommatophora (Stylommatophora)
Family	Betulaceae	Clausiliidae
Genus	Alnus	Clausilia
Species	Alnus serrulata	Clausilia bidentata

Conservation Status

Brook-Side Alder

LC — Least Concern

common door snail

LC — Least Concern

Physical Characteristics

Attribute	Brook-Side Alder	common door snail
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Brook-Side Alder

Habitat

Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

Range

Distributed across Canada and United States.

common door snail

Habitat

Typically found in terrestrial and aquatic habitats including forests and freshwater.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Brook-Side Alder

The Brook-Side Alder (Alnus serrulata) is a species in the genus Alnus. It is currently classified as Least Concern on the IUCN Red List. Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

common door snail

<em>Clausilia bidentata</em>, the common door snail, is a terrestrial gastropod mollusk in the family Clausiliidae. This species is distributed across Belgium, Denmark, Norway, and Sweden, where it typically inhabits moist terrestrial environments including deciduous woodlands, rocky slopes, hedgerows, and the margins of freshwater habitats. The common door snail is recognized by its elongated, sinistral (left-handed) shell, which is a distinctive trait of the family Clausiliidae. The shell is typically brown to gray and reaches approximately 12–15 millimeters in length. <em>Clausilia bidentata</em> generally feeds on algae, lichens, fungi, and decaying plant material by rasping food with a radula. It often shelters under bark, stones, and leaf litter during dry or cold conditions. Like many clausiliids, it possesses a complex internal shell structure called a clausilium that closes the shell aperture to reduce desiccation. The species is assessed as Least Concern, reflecting stable populations across its European range. Detailed biological traits beyond those noted here are not extensively documented in the current scientific literature.