Raft spider
Encyclopedia
The raft spider, Dolomedes fimbriatus, is a European spider
of the family Pisauridae. The raft spider is one of the two largest spiders in the United Kingdom
. Like other Dolomedes
spiders it hunts by running on the surface of water, and can submerge altogether to hide from predators.
The female's body measures up to 22 millimetre (0.866141732283465 in) long with a leg span of about 70 mm (2.8 in); as with most spiders the male is considerably smaller.
Raft spiders are semi-aquatic and live around acid
ic bog
s and in wet acidic grassland
, especially where there are small pools of water. They are dark chocolate brown in colour (or sometimes greenish) with a conspicuous white or cream stripe along each side. The closely related great raft spider
(Dolomedes plantarius) is similar in size, habits and appearance, but lives in fen
s.
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
of the family Pisauridae. The raft spider is one of the two largest spiders in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
. Like other Dolomedes
Dolomedes
Dolomedes is a genus of large spiders of the family Pisauridae. They are also known as fishing spiders, raft spiders, dock spiders or wharf spiders. Almost all Dolomedes species are semi-aquatic, with the exception of the tree-dwelling D. albineus of the southwestern United States...
spiders it hunts by running on the surface of water, and can submerge altogether to hide from predators.
The female's body measures up to 22 millimetre (0.866141732283465 in) long with a leg span of about 70 mm (2.8 in); as with most spiders the male is considerably smaller.
Raft spiders are semi-aquatic and live around acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
ic bog
Bog
A bog, quagmire or mire is a wetland that accumulates acidic peat, a deposit of dead plant material—often mosses or, in Arctic climates, lichens....
s and in wet acidic grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
, especially where there are small pools of water. They are dark chocolate brown in colour (or sometimes greenish) with a conspicuous white or cream stripe along each side. The closely related great raft spider
Great raft spider
The great raft spider or fen raft spider is a European species of spider in the Pisauridae family. Like other Dolomedes spiders, it is semi-aquatic, hunting its prey on the surface of water...
(Dolomedes plantarius) is similar in size, habits and appearance, but lives in fen
Fen
A fen is a type of wetland fed by mineral-rich surface water or groundwater. Fens are characterised by their water chemistry, which is neutral or alkaline, with relatively high dissolved mineral levels but few other plant nutrients...
s.