Dumb-bell worms

The dumb-bell worms (Family Sternaspidae) are a small group of worms that burrow in the sediment. When partially contracted they can appear peanut-shaped, but when completely retracted they seem almost spherical or gourd-shaped. There is only one genus in this family and possibly only one species in the Pacific Northwest, although there are unresolved records. Historically, the ground-digger dumb-bell worm (AN48) living in the Pacific Northwest was determined as Sternaspis scutata, a species originally described from the Mediterranean Sea. However, recent investigations have equated this local worm with Sternaspis fossor, a species originally described from the Bay of Fundy on the east coast of Canada. Future investigations may change perceptions again. Another species is known to occur off California and perhaps yet a different one from Japan (or is it Sternaspis scutata?). Little is known about the reproduction or larval development of the dumb-bell worms, although their specialized genital papillae (fleshy projections) may be used for copulation.