Brook Floater vs common door snail

Alasmidonta varicosa compared with Clausilia bidentata

Key Differences

• Brook Floater is Vulnerable while common door snail is Least Concern.

Taxonomic Classification

Rank	Brook Floater	common door snail
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Mollusca (Mollusks)	Mollusca (Mollusks)
Class	Bivalvia (Bivalvia)	Gastropoda (Gastropoda)
Order	Unionida (Unionida)	Stylommatophora (Stylommatophora)
Family	Unionidae	Clausiliidae
Genus	Alasmidonta	Clausilia
Species	Alasmidonta varicosa	Clausilia bidentata

Evolutionary Relationship

Brook Floater and common door snail share a common ancestor at the Phylum level: Mollusca. (Mollusks)

Conservation Status

Brook Floater

VU — Vulnerable

common door snail

LC — Least Concern

Physical Characteristics

Attribute	Brook Floater	common door snail
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Brook Floater

Habitat

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

Range

Found in United States. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

common door snail

Habitat

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

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Brook Floater

The Brook Floater (Alasmidonta varicosa) is a species in the genus Alasmidonta. It is currently classified as Vulnerable on the IUCN Red List. Native to North America, inhabiting ecosystems characteristic of the region.

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.