(Jeffreys, 1865) 
The razor shell, Ensis arcuatus, also called razor clam or razor fish, is a bivalve of the family Pharidae. It is found on sandy beaches in Northern Europe and Eastern Canada, such as Prince Edward Island, where it is most populous in the world. In some locations, "razor shell" can also refer to members of the family Solenidae, including species of the genera Ensis and Solen, by some taxonomic classifcations which include the family Pharidae within the family Solenidae. It prefers coarser sand than its relatives E. ensis and E. siliqua.
It is known for its elongated, rectangular shape, whose similarity to the straight razor gives it its name. The razor shell has been known to reach 23 centimetres (9.1 in) in length. The dorsal margin is straight while the ventral margin is curved. It can easily be confused with the slightly shorter 15 centimetres (5.9 in) and more curved E. ensis (in which both front and back are curved in parallel).
Razor shells have a fragile shell, with open ends. The shell is smooth on the outside and whitish in color, with vertical and horizontal reddish-brown or purplish-brown markings separated by a diagonal line. The periostracum is olive-green. The inner surface is white with a purple tinge and the foot is creamy white with brown lines.
The razor shell lives under the sand, using its powerful foot to dig to a safe depth. Its digging activity comprises six stages, repeated cyclically. A digging cycle involves integration of the muscular foot (which takes up a large part of the body) with the opening and closing of the valve and one end. The foot is inflated hydraulically, extend down into the sand and anchoring the animal. Deflation of the foot then draws the shell down. The razor shell also squirts water down into the sand, removing loose sand from its path. The foot is thought to exert a pressure of 2 kg/cm2
In the razor shell sexual development is highly synchronous. During the summer, they are in the sexual rest stage, and gametogenesis begins at the start of autumn. In winter and spring consecutive spawns take place, interrupted by gonadal restoration periods.
- S. Gofas (2010). "Ensis arcuatus (Jeffreys, 1865)". In P. Bouchet, S. Gofas & G. Rosenberg. World Marine Mollusca database. World Register of Marine Species. Retrieved August 11, 2010.
- Breen, Mike; Trevor Howe and Phil Copland (February 2011). "A REPORT ON ELECTRICAL FISHING FOR RAZOR CLAMS (ENSIS SP.) AND ITS LIKELY EFFECTS ON THE MARINE ENVIRONMENT". Marine Scotland Science Report 03/11 (Marine Scotland Science Marine Laboratory): 11. Retrieved 24 January 2014.
- Large specimen.
- E. R. Trueman (1967). "The dynamics of burrowing in Ensis (Bivalvia)". Proceedings of the Royal Society of London B 166 (1005): 459–476.
- Susana Darriba, Fuencisla San Juan & Alejandro Guerra (2004). "Reproductive cycle of the razor clam Ensis arcuatus (Jeffreys, 1865) in northwest Spain and its relation to environmental conditions". Journal of Experimental Marine Biology and Ecology 311 (1): 101–115. doi:10.1016/j.jembe.2004.05.004.
- Emerging from their burrows