Keyhole Limpet

Giant Keyhole Limpet

Megathura crenulata

Physical Description

The Giant Keyhole Limpet has a shell permanently covered by mantle, reaching lengths of up to 250 mm. Its soft parts are typically solid black but may also appear mottled. The bottom of its foot is yellowish-brown.


Commonly found on rocks in kelp forests.

Geographical Range

From Monterey Bay to Baja.


Feeds on compound ascidians and other encrusting invertebrates.

Other Species