Slipper Limpet

Crepidula fornicata


Habitat: Marine. Found in the area around the low water mark and into the shallow subtidal


Description: This species has an oval shell, up to 5 cm in length, with a much reduced spire. The large aperture has a shelf, or septum, extending half its length. The shell is smooth with irregular growth lines and white, cream, yellow or pinkish in colour with streaks or blotches of red or brown. Slipper limpets are commonly found in curved chains of up to 12 animals. Large shells are found at the bottom of the chain, with the shells becoming progressively smaller towards the top.


Origin and Distribution: Originally found on the east coast of the Americas between Canada and Mexico. Now introduced to British-Columbia, Washington state, Japan and Europe, where it is found on the Atlantic coast between Denmark and Spain, in Sicily and the Adriatic Sea.


Impacts: In shallow bays where the slipper limpet has been introduced in France, it can completely smother the sediment creating beds with several thousand individuals per m2. Dense aggregations of slipper limpet trap suspended silt, faeces and pseudofaeces altering the benthic habitat. Where slipper limpet stacks are abundant, few other bivalves can live amongst them. The slipper limpet is a serious threat to oyster beds because of this.

It has also been observed that live maerl thalli, which are a protected species and form an important protected habitat, become covered in slipper limpets and the spaces between the thalli of the bed become clogged with silt; this kills the maerl thalli and dramatically alters associated communities. No management measures have proven effective for this species in this habitat.


Where is it found in Ireland? The only recorded viable population in Ireland was documented in 2009 in Belfast Lough. Other records exist from around Ireland over the last century including: Ballinakill Bay, Carlingford Lough, Dungarven Bay, Kenmare Bay and Clew Bay. However, none of these sites are currently thought to be supporting C. fornicata.


How did it get here? C. fornicata most likely arrived in Ireland with consignments of mussels. Other possible pathways include; with consignments of oysters, on drifting materials or due to dispersal of larvae.


Prevent Spread

Aquaculture managers and owners should avoid getting spat material from areas that are known to have slipper limpet present or nearby.

Invasive Species Ireland

Invasive Species Ireland