Gastropods · Trochida · Trochidae

Flat Top Shell

Gibbula umbilicalis

Not Evaluated

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

A small snail with a flattened conical shell, grey with oblique violet bands and a deep, open umbilicus at the base. It grazes biofilm and microalgae from intertidal rocks and is one of the most abundant species on the rocky Atlantic shores of western Europe.

Size

up to 2.2 cm

Diet

Herbivore

Feeds mainly on plants.

Social structure

Colony

Lives in large concentrations, often for breeding reasons.

Sighting difficulty

Unknown

OceanHerbivore Colonial Ocean Mollusc

13countries 20parks 17dive sites

Fun facts

It is one of the species biologists use as an indicator of sea warming: its distribution has shifted northwards in recent decades.
The open, deep umbilicus distinguishes it from other top shells of the same habitat.
It is identified by its umbilicus: a deep, round hole in the centre of the shell's base, which gives it its name.
Its shell carries oblique violet bands on a grey ground, a pattern easily recognised on Atlantic rocks.
It scrapes the biofilm of microscopic algae off the rock with its radula, and its grazing keeps rock surfaces clear.
Its northern limit is shifting as the sea warms, and it is used as an indicator of climate change on British coasts.