Crangon crangon

Crangon crangon is a commercially important species of caridean shrimp fished mainly in the southern North Sea, although also found in the Irish Sea, Baltic Sea, Mediterranean Sea, and Black Sea, as well as off much of Scandinavia and parts of Morocco's Atlantic coast. Its common names include brown shrimp, common shrimp, bay shrimp, and sand shrimp, while translation of its French name crevette grise (or its Dutch equivalent grijze garnaal) sometimes leads to the English version grey shrimp. Adults are typically 30–50 mm (1.2–2.0 in) long, although individuals up to 90 mm (3.5 in) have been recorded. The animals have cryptic colouration, being a sandy brown colour, which can be changed to match the environment. They live in shallow water, which can also be slightly brackish, and feed nocturnally. During the day, they remain buried in the sand to escape predatory birds and fish, with only their antennae protruding. Crangon is classified in the family Crangonidae, and shares the family's characteristic subchelate first pereiopods (where the movable finger closes onto a short projection, rather than a similarly sized fixed finger) and short rostrum. C. crangon has a wide range, extending across the northeastern Atlantic Ocean from the White Sea in the north of Russia to the coast of Morocco, including the Baltic Sea, as well as occurring throughout the Mediterranean and Black Seas. Despite its wide range, however, little gene flow occurs across certain natural barriers, such as the Strait of Gibraltar or the Bosphorus. The populations in the western Mediterranean Sea are thought to be the oldest, with the species' spread across the north Atlantic thought to postdate the Pleistocene. Adults live epibenthically (on or near the sea-floor) especially in the shallow waters of estuaries or near the coast. It is generally highly abundant, and has a significant effect on the ecosystems where it lives. Females reach sexual maturity at a length around 22–43 mm (0.87–1.69 in), while males are mature at 30–45 mm (1.2–1.8 in). The young hatch from their eggs into planktonic larvae. These pass through five moults before reaching the postlarval stage, when they settle to the sea-floor. Historically, the commercial fishery was accomplished on horseback on both sides of the Dover straits. Over 37,000 t of C. crangon were caught in 1999, with Germany and the Netherlands taking over 80% of this total.