Brook Floater vs Coastal Flat-body

Alasmidonta varicosa compared with Agonopterix yeatiana

Key Differences

• Brook Floater is Vulnerable while Coastal Flat-body is Near Threatened.

Taxonomic Classification

Rank	Brook Floater	Coastal Flat-body
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Mollusca (Mollusks)	Arthropoda (Arthropods)
Class	Bivalvia (Bivalvia)	Insecta (Insects)
Order	Unionida (Unionida)	Lepidoptera (Butterflies & Moths)
Family	Unionidae	Depressariidae
Genus	Alasmidonta	Agonopterix
Species	Alasmidonta varicosa	Agonopterix yeatiana

Evolutionary Relationship

Brook Floater and Coastal Flat-body share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Brook Floater

VU — Vulnerable

Coastal Flat-body

NT — Near Threatened

Physical Characteristics

Attribute	Brook Floater	Coastal Flat-body
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.

Coastal Flat-body

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, and Sweden. Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

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.

Coastal Flat-body

Agonopterix yeatiana, the coastal flat-body, is a small moth in the family Depressariidae native to coastal and calcareous grassland habitats across western and northern Europe, with records from Belgium, Denmark, and Sweden. Moths in the family Depressariidae, commonly called flat-body moths due to the depressed posture they adopt when resting with wings held flat against the surface, are associated predominantly with umbellifer plants of the family Apiaceae as larval hosts. Agonopterix yeatiana larvae feed on wild carrot (Daucus carota), wild parsnip (Pastinaca sativa), and related coastal and grassland Apiaceae species, inhabiting the open, often calcareous or sandy habitats where these plants grow. Adult moths have greyish-brown forewing with a distinctive pattern of spots and dashes and reach approximately 8–12 millimeters in wingspan. The species is classified as Near Threatened by the IUCN, reflecting declines associated with the loss of traditional hay meadow management, coastal grassland degradation, and scrub encroachment that eliminates the open, flower-rich grassland habitats supporting its host plants. Agricultural intensification has reduced wild umbellifer populations significantly across lowland Europe, reducing food resources for larvae of specialist moths like A. yeatiana.