There are two subspecies described for this species, one for the Atlantic and one for the Mediterranean and Black Seas. But this appears to be invalid (Stefanni et al. 2003).

The population of this species in the Mediterranean Sea has suffered serious declines in the range of 80% over the last 10 years in the Gulf of Lion, France and Gulf of Genova, Italy, where it is estimated that at least 50% of its population may occur. However, information for its population in the Aegean Sea or Adriatic Sea is not known. Threats to the species throughout the Mediterranean Sea include the incidental capture in fishery activities, and in at least half of its range, the loss of habitat due to the warming of waters related to climate change. Therefore this species is listed as Vulnerable in the Mediterranean Sea, with an estimated decline of approximately 40% over the past 10 years. With additional data from the Black Sea, the Aegean Sea and the Adriatic Sea, this reassessment of this species may warrant a higher regional threat category.

This species is present in the east Atlantic from Norway to Spain (Rochard and Elie 1994).

It is also found in the Mediterranean Sea (Rochard and Elie 1994), including Monaco and the Lavezzi Islands, the north Aegean Sea, Sea of Marmara and the Black Sea.

This is a relict species that is has suffered serious declines in the Mediterranean Sea due to temperature increases related to climate change (Lejeusne et al. 2010), as it is a colder water species. Based on surveys, there is an estimated population decline of at least 80% over the past 10 years in the Gulf of Lion, France and the Gulf of Genova, Italy (J.P. Quignard pers. comm. 2007), where it is estimated that at least 50% of the Mediterranean population may occur. This species is not abundant in the Black Sea and Sea of Marmara, and there is no information on the population in the Aegean Sea or Adriatic Sea.

This occasionally schooling species is found in inshore sandy and muddy areas. Juveniles are found in lower estuaries. The main depth range is 1-20 m although it has been found down to 200 m. Mainly diurnal, this species feeds on small polychaetes, amphipods (corophiids, caprellids), cumaceans and mysids (Miller 1986). It spawns in summer in shallow waters. The male lures the female into an empty bivalve shell where she lays a portion of eggs. The eggs are guarded by the male for 10 days until larvae about 3 mm long. Larvae are pelagic at first. Young fish only start to live at the bottom when 17-18 mm (Muus and Nielsen 1999).

This species is captured as bycatch in fixed nets and trap nets in most of its range. Climate change resulting in warmer waters and loss of habitat in the Mediterranean Sea is also a major threat.

This species is listed in Annex III of the Bern Convention.