Common name(s): Keyhole limpet, Rough keyhole limpet, volcano limpet
|Diodora aspera at Rosario|
|(Photo by: Dave Cowles, 1997)|
How to Distinguish from Similar Species: In Puncturella and Fissurella species the dorsal hole is an elongated slit. Megathura crenulata (the giant keyhole limpet) lives farther south, grows much larger, and the mantle covers much to all of the shell when the animal is alive.
Geographical Range: Afognak Island, Alaska to Camalu, Baja California.
Depth Range: Low intertidal to subtidal
Habitat: Common in rocky areas all along the coast
Biology/Natural History: Species is omnivorius but prefers encrusting bryozoans. Extends its mantle extremely when it encounters a seastar predator (such as Pycnopidia, Leptasterias, Pisaster, or Orthasterias) so that the shell is largely covered and the seastar has no place to grab onto the shell. Often contains a symbiotic polychaete worm Arctonoe vittata (picture) in its mantle cavity which may bite the seastar as well. Diodora's blood contains hemocyanin, has a low pH (7.1) and no Bohr effect.
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Morris et al., 1980
View of the underside of the animal showing the foot, head with antennae (left), mantle cavity, and mantle. Dave Cowles 1997
A specimen in a cave at Cape Flattery, 2004 (Dave Cowles), along with its commensal polychaete flatworm, Arctonoe vittata. Note ridges and color pattern on shell.
This individual is in the intertidal in Deception Pass. Photo by Dave Cowles, April 2007
This individual, partly encrusted with bryozoans, was on Swirl Rocks. Photo by Dave Cowles, July 2007