Platorchestia platensis

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Platorchestia platensis (Krøyer, 1845) is a species of sand flea, a small amphipod crustacean that lives on beaches. It belongs to the family Talitridae and, like other sand fleas, stays in moist sand or among rotting seaweed above the wet shoreline. It competes with the native Orchestia gammarellus on European beaches, often pushing it out. Its native range is not exactly known, but it is thought to be circumtropical. The species was described from samples near Montevideo, Uruguay, and is believed to spread through ships’ ballast water. It was first found in northern Europe in 1860 on a beach near Humlebæk, Denmark. By the 1940s it was common on both sides of the Kattegat; it reached the Netherlands around 1950, and the United Kingdom in 1978. It was originally named Orchestia platensis by Henrik Nikolai Krøyer in 1845, based on material from the Río de la Plata in Uruguay. A synonym is Orchestia agilis.