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Guide to New Zealand's freshwater invertebrates
Water spiders
(
Pisauridae
: Dolomedes
)
Diagnostic features
Dolomedes is a genus of spiders that includes species capable of entering the water. They are quite large, reaching up to 75mm in leg span. Dolomedes are known as “nursery web” spiders due to their nests made of dense blankets of web often seen on the outer branches of bushes.
Typical habitats
Dolomedes can be common along the stony or weedy margins of streams and rivers. They are usually seen above the water, but they can retreat into the water by climbing down emergent vegetation.
Feeding
They are predators of invertebrates (possibly also small fish), and have been seen catching stream insects as they emerge from the water.
Indicator value
Dolomedes are found along farmland and urban streams, and since they live primarily above the water they may not be very sensitive to water quality. They have been assigned tolerance values of 5 (hard bottom sites) and 6.2 (soft bottom sites).
