Great raft spider
| Great raft spider | |
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| An adult female great raft spider on the surface of a water pool | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Arachnida |
| Order: | Araneae |
| Family: | Pisauridae |
| Genus: | Dolomedes |
| Species: | D. plantarius |
| Binomial name | |
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Dolomedes plantarius (Clerck, 1757) |
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| Countries with a recorded population of D. plantarius. | |
| Synonyms | |
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Araneus plantarius |
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Araneus plantarius
Aranea viridata
Dolomedes riparius
The great raft spider or fen raft spider (Dolomedes plantarius) 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. It occurs mainly in neutral to alkaline, unpolluted water of fens and grazing marsh.
The species was first described by arachnologist Carl Alexander Clerck in 1757 as Araneus plantarius. Its genus was reclassified by Pierre André Latreille in 1804 to Dolomedes. The species has also been described under the name Aranea viridata by Müller and as Dolomedes riparius by Hahn.
The species is currently recognised as Dolomedes plantarius and has two widely recognised common names; the great raft spider and the fen raft spider.
D. plantarius is a large species within its range. Adult females can have bodies of slightly over 20mm in length with a span of 70mm including their legs. It is typically black or brown in colouration with white or cream stripes along the sides of the body. It is very similar in look to the closely related raft spider Dolomedes fimbriatus with which it is often misidentified.
The great raft spider, as with most other Dolomedes species, is a semi-aquatic spider. It inhabits lowland fen and grazing marsh areas and is dependent on the presence of standing or slow moving neutral to alkaline water. Within these areas it can be found on the margins of pools or ditches. Emergent vegetation is highly important for use as perches for hunting and basking and to support nursery webs. As a warmth loving species they avoid areas where water surfaces are shaded.
Great raft spiders are predatory and hunt from perches at the waters edge. They primarily feed on aquatic invertebrates such as pond skaters, dragonfly larvae, small fish and smaller aquatic spiders. They will also feed on drowning terrestrial invertebrates and have been known to catch small vertebrates such as sticklebacks and tadpoles.
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Wikipedia