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Family  Vulsellidae

Sponge Finger or Butterfly Shells

The Vulsellidae is a numerically small family of fragile bivalves containing the genera Vulsella, Electroma and Crenatula. The number of Vulsella species has long been debated. Huber (2010) summarised the number of species accepted over the years: Lamarck (1819) accepted six; Reeve (1858) accepted 17; E.A. Smith accepted four; Fischer-Piette (1977) accepted one (see Huber (2010) for references). Huber himself accepted five species, but his Australian species are not beyond question.

Vulsella species live permanently embedded in sponges, with only the ventral end of the shell projecting. Clumps of sponge with dozens of embedded shells are sometimes washed up on beaches. Electroma are thin and fragile Butterfly Shells that live attached by a byssus to sponges, corals or seagrass.

Family Reference: Huber’s Compendium of Bivalves illustrates the species worldwide.

Coverage: Only two species of the family occur in NSW; both are treated here.

Identification Notes: Shells of Vulsella are easily identified from their habitat of being embedded in sponges. Those of Electroma are thin and fragile, and often cast up on southern Australian beaches in large numbers.