Rough Keyhole Limpet (Diodora aspera)

Description: The rough keyhole limpet has a hole in the top point of their shells. As their name suggests, the outside of this species’ shell has a rough texture and often has bryazoans and barnacles growing on it. Rough keyhole limpet can grow large, sometimes up to 7 cm across! Unlike many other species of limpet, it is possible to see the “mantle” or flesh of the limpet when the tide is out. If you look closely you may even see a set of antenna.

Habitat: Rough keyhole limpets range from Alaska to Nicaragua. They live on rock in the intertidal and sub-tidal zones. At Haystack Rock they are usually found in the lower intertidal zone by The Needles.

Diet: Grazing on rocks, rough keyhole limpets eat bryozoans, algae, and sponges.

Tide Pool Tidbits:

• Scale worms (Arctonoe vittata) sometimes live underneath the shells of rough keyhole limpets. Their relationship is symbiotic, meaning that both the limpet and the worm benefit from living together. The scale worm occasionally slides out from underneath the limpet’s shell to bite the tube feet of sea stars coming to eat the limpet; this means that limpets are protected from being eaten, and scale worms get to travel under the protection of a shell while they search for food!

• The rough keyhole limpet is actually not considered a true limpet. It is more closely related to abalone than true limpets.

References: New World Encyclopedia, Central Coast Biodiversity