Coastal Silver-stiletto vs hydroid

Acrosathe annulata compared with Obelia longissima

Key Differences

• Coastal Silver-stiletto is Least Concern while hydroid is Not Evaluated.

Taxonomic Classification

Rank	Coastal Silver-stiletto	hydroid
Kingdom same	Animalia (животные)	Animalia (животные)
Phylum	Arthropoda (членистоногие)	Cnidaria (стрекающие)
Class	Insecta (насекомые)	Hydrozoa (гидроидные)
Order	Diptera (двукрылые)	Leptothecata (Leptothecata)
Family	Therevidae	Campanulariidae
Genus	Acrosathe	Obelia
Species	Acrosathe annulata	Obelia longissima

Evolutionary Relationship

Coastal Silver-stiletto and hydroid share a common ancestor at the Kingdom level: Animalia. (животные)

Conservation Status

Coastal Silver-stiletto

LC — Least Concern

hydroid

NE — Not Evaluated

Physical Characteristics

Attribute	Coastal Silver-stiletto	hydroid
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Coastal Silver-stiletto

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

hydroid

Habitat

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

Range

Widely distributed across Europe (4 countries), North America (United States), Oceania and the Pacific (Australia, New Zealand), and South America (Argentina).

Coastal Silver-stiletto

Coastal silver stiletto (Acrosathe annulata) is a slender robber fly in the family Therevidae, native to northwestern Europe, including the United Kingdom, France, the Netherlands, Belgium, and Scandinavia. Adults are found on coastal sand dunes and sandy heathland, where they perch on bare sand to ambush small flying insects. Stiletto flies in the family Therevidae are characterised by a slender body, long pointed abdomen, and predatory habits; adults prey on a variety of small dipterans and other flying insects during warm, sunny periods. Larvae develop in sandy soil, where they are also predatory, feeding on other invertebrate larvae. Acrosathe annulata is a habitat specialist restricted to open, sandy coastal habitats with sparse vegetation—environments that have declined substantially across northwestern Europe due to dune stabilisation, recreational disturbance, and the cessation of traditional dune management. The IUCN lists it as Least Concern, though regional conservation bodies in the United Kingdom have flagged population declines. It is considered an indicator of high-quality coastal sand dune habitats and is monitored through national invertebrate surveys.

Shared Countries

Both species can be found in 4 countries:

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