Channeled Whelk
(Busycotypus canaliculatus)

Description: The long siphonal canal is diagnostic in this species of whelk. The aperture or opening of the shell is large and lacks a fold on the outer lip. The sutures are distinct and resemble a spiral staircase. The shell is smooth and virtually without sculpturing, and grows to 18 cm in length; it is larger than our native bay snails. It is usually brown or orange, but on rare occasions can be white or light purple. The egg capsules of this species can be found daisy-chained together in strings, and are often washed ashore.

Habitat: In bays. During the winter they are found in fairly shallow intertidal areas over mud, but during the summer they migrate to deeper waters.

Origin: East Coast of North America.

Invaded Areas: San Francisco Bay.

Concerns: The channel whelk preys on bivalves, and if abundant, can seriously affect native clam and oyster populations, while outcompeting native predatory snails. Their floating egg cases have the potential to expand the distribution of the snail within bays, as well as to spread it between bays. This species is sold in the aquarium trade, and also is the basis for a fishery on the East Coast. It invaded San Francisco Bay around 1940, and became abundant there.