Rough Keyhole Limpet

Diodora aspera

Rough Keyhole Limpet

Diodora aspera

Other Common Names
Keyhole limpet, Volcano limpet

Sandy Coast

Other Common Names

Keyhole limpet, Volcano limpet

At the Aquarium

Sandy Coast

Appearance

Caplike shell that is often gray or gray-brown with coarse radial ribs; may also have black and white radiating stripes. At the apex of the shell there is an oval opening about 1/10th the length of the shell. There may be other organisms growing on the shell, including tunicates, sponges, and bryozoans.

Habitat

Rocky areas from the low intertidal and subtidal zones to depths of 40 ft.

Diet

Omnivore whose diet includes encrusting byrozoans, sponges, and algae.

Life History

Keyhole limpets have separate sexes. They broadcast spawn and the larvae start life as free-floating plankton. These snails can reach lengths of up to 3 in.

IUCN Status

Not Evaluated

Ecosystem & Cultural Importance

These snails feed by scraping rocky surfaces with their tongue-like radula. They are important to their intertidal habitats–by scraping algae and other encrusting organisms off of rocks, they clear space for new larval organisms to settle, such as mussels and barnacles.

Often provides a home to a scale worm, which lives in its mantle cavity. When a seastar tries to attack the limpet, the scale worm may also bite at the seastar’s tube feet.

Predators include the sunflower star, ochre star, and false ochre star.

Alaska to Baja California, Mexico

You can find these snails in tide pools along the Oregon coast.

When a sea star approaches the limpet, it will protect itself by covering its shell so that the sea star cannot get a good grip with its tube feet. The limpet will rise to twice its normal height, extending part of its mantle up and over the shell while another part of its mantle moves down to cover the side of the foot, while also extending its siphon out of its hole.

Keyhole limpets are not considered ‘true’ limpets because of how they take in water. True limpets draw in water from their left side, pass it over their single gill, and then it exits out their right side. In keyhole limpets, they draw in water through both sides, it flows over their paired gills, and then it flows out through the keyhole opening at the top of the shell.

Citations & Other Resources

A Snail’s Odyssey website: https://www.asnailsodyssey.com/
Animal Diversity Web: https://animaldiversity.org/accounts/Diodora_aspera/
Invertebrates of the Salish Sea website: https://inverts.wallawalla.edu/Mollusca/Gastropoda/Prosobranchia/Order_Archaegastropoda/Suborder_Pleurotomariina/Fissurellidae/Diodora_aspera.html

Rough Keyhole Limpet

Rough Keyhole Limpet

Other Common Names

At the Aquarium

Appearance

Habitat

Diet

Life History

IUCN Status

Ecosystem & Cultural Importance

Citations & Other Resources

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