Crepidula fornicata has not been reported from Australia. The species has been reported from Irish waters (McNeill et al., 2010) and the Aegean Sea (Doğan et al., 2014), indicating a current and continuing spread in Europe.

An understanding of the reproductive- and settlement properties of C. fornicata with regards to its potential northward spread in Europe has commanded some attention in recent years, with complex results. A study by Pechenik et al., (2017) compared populations from two sites along the Norwegian coastline with that of females collected from Rhode Island, USA. They reported that fecundities increased with increasing shell length, and that size-related fecundities were significantly higher for Norwegian females, which also produced larger egg capsules and a greater number of embryos per capsule (but not a greater number of egg capsules per brood). Thus, they suggested that at the northern extreme of its invaded range, the fecundity of C. fornicata is comparatively high. However, the risk of northward spread may be somewhat tempered by the temperature sensitivities for larval settlement; a study by Bohn et al., (2012) reported that benthic recruitment in the northern introduced range of the species was observed over a much shorter period (at seawater temperatures <16 °C) than that of populations to the south. They proposed that its northwards spread will not be limited by seawater temperature negatively affecting reproduction, but by processes acting after larval release.

Crepidula fornicata can be observed in bays and estuaries, and on grounds inshore (Blanchard, 1997). This gregarious gastropod lives in stacks* of several individuals and forms extended beds in shallow subtidal areas (Androuin et al., 2018).

C. fornicata is native to the Atlantic coast of America, from Canada to Texas (Zenetos et al., 2003). It was first inadvertently introduced into the coastal waters of the UK in the 1870s, likely translocated with oysters from North America (e.g. McMillan, 1938; Blanchard, 1997). C. fornicata is now common along the coasts of France, the Netherlands, Germany, Denmark, Ireland, and Norway, with adult densities of thousands of individuals per m² in some locations (reviewed by Blanchard 1997, 2009; Thieltges et al., 2004; McNeill et al., 2010; Bohn et al., 2012). Abundances at its northern and southern geographical range limit are relatively low, while very dense populations occur in France and the UK (Bohn et al., 2012 and references therein).

Crepidula fornicata is a benthic gastropod that bears a calcareous and slightly spiralled shell with a maximum length of 58 mm (Blanchard, 1997). It is an arched mollusc with brown markings and an apex that is bent downward to one side at the back. The shell is convex, ovate and rather thin with an edge that is cutting. The outer surface is completely smooth or with only growth lines.

C. fornicata has an elongate, oval aperture (shell opening), with a projecting plate or shelf extending for approximately half the length of the shell (hence ‘slipper’ limpet).

This species has not been recorded in Australia to date.

*An image of a C. fornicata stack can be found at:

https://northernireland-species.nbnatlas.org/species/NBNSYS0000174750