The killer shrimp (Dikerogammarus villosus) is a shrimp species from the waters of Eastern Europe, including the Black and Caspian Seas. Many invaders originate in this region, where East meets West. This particular species has begun invading Western Europe and the waters of the Mediterranean.
Killer shrimp reproduce and grow very fast; they reach sexual maturity in just four to eight weeks. They also attack native species at random, killing small fish, nymphs, leeches and the eggs of other small vertebrates -- often with no intention of eating their prey.