Gastropods · Vetigastropoda · Fissurellidae

Common Keyhole Limpet

Diodora graeca

Not Evaluated

It has not yet been assessed against the IUCN criteria. See full glossary

A limpet with a conical shell pierced by a hole at the apex, clinging to rocks and often under stones. Unlike the true limpets, it does not graze algae: it feeds on encrusting sponges. Water enters beneath the edge of the shell, passes over the gills and leaves through the apical hole along with the waste.

Size

up to 3.5 cm

Diet

Carnivore

Feeds mainly on other animals.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Unknown

OceanCarnivore Solitary Ocean Mollusc

24countries 31parks 62dive sites

Fun facts

The hole at the apex is an outlet for water and waste: a one-way circulation system that keeps the gills from being fouled.
The mantle can fold back over the edge of the shell and partly cover it.
It is not a true limpet. Keyhole limpets have a hole at the apex of the shell through which they expel respiratory water and waste, so that intake and outflow are separate.
Unlike grazing limpets, it eats sponges, above all of the genus Halichondria.
It is a protandrous hermaphrodite: it matures as a male and changes to female as it grows.