Raft Spider
CR

Raft Spider

Dolomedes fimbriatus

Unknown

Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/Raft_spider

Overview

The raft spider, scientific name Dolomedes fimbriatus, is a large semi-aquatic spider of the family Dolomedidae found throughout north-western and central Europe. It is one of only two species of the genus Dolomedes found in Europe, the other being the slightly larger Dolomedes plantarius which is endangered in the UK.

The Raft Spider faces severe population declines due to widespread habitat destruction and degradation of wetland ecosystems across its range. Water pollution, drainage of marshlands for agriculture and development, and climate change-induced alterations to water levels have dramatically reduced suitable habitat availability. Conservation status may vary by region or assessment authority, but the species remains highly vulnerable to continued wetland loss.

Threat summary

Habitat

Inhabits shallow, nutrient-rich freshwater wetlands including pond margins, ditches, fens, marshes, and slow-moving streams with abundant emergent vegetation. Requires areas with floating vegetation mats and overhanging plants that provide hunting platforms and refuge sites near the water surface.

Threatened in Åland Islands

Calidris ferrugineaVU

Calidris ferruginea

Declining
Scarce BlackneckCR

Scarce Blackneck

Lygephila craccae

Unknown
EN

knopphodeedderkopp

Walckenaeria nodosa

Unknown
EN

Dolichopus notatus

Unknown

Frequently asked questions

Why is Raft Spider classified as Critically Endangered?
Raft Spider is classified as Critically Endangered — facing an extremely high risk of extinction in the wild — because population sizes are very small, declining sharply, or restricted to a tiny range. The Raft Spider faces severe population declines due to widespread habitat destruction and degradation of wetland ecosystems across its range. Water pollution, drainage of marshlands for agriculture and development, and climate change-induced alterations to water levels have dramatically reduced suitable habitat availability. Conservation status may vary by region or assessment authority, but the species remains highly vulnerable to continued wetland loss.
Where does Raft Spider live?
Raft Spider occurs in Åland Islands, Australia, Austria, Belarus, Belgium, and Croatia (plus 28 other countries). Country-level distribution data is sourced from the IUCN Red List and cross-referenced with GBIF occurrences.
What are the main threats to Raft Spider?
The main threats to Raft Spider are ai-1, ai-2, ai-3, and ai-4. The full IUCN-classified threat record for this species is detailed on the species page.

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