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Mussel

Guide to New Zealand's freshwater invertebrates

Mussel ( Hyriidae : Echyridella )

Echyridella juvenile
Echyridella adult burrowed into sand

Diagnostic features

Echyridella (formerly Hyridella) is a genus of native freshwater mussels. The shells of large individuals are thick and darkly coloured, but the shells of juveniles are usually pale. Echyridella burrows into soft sediments; they have no ability to attach to rocks with threads (many marine mussels use such threads). Because of this burrowing, typically only one end of the shell (with siphons) is visible above the sediment.

Typical habitats

Echyridella are most common in lakes and soft-bottom, slow-flowing streams and rivers.

Feeding

They are filter feeders, extracting fine particles of organic matter (including plankton) from the water.

Indicator value

Echyridella can be abundant in pristine and degraded waters. We know little about their ability to tolerate specific types of pollution. They have been assigned tolerance values of 3 (hard bottom sites) and 6.7 (soft bottom sites).