Eriocheir

Eriocheir is a genus of crabs, commonly known as mitten crabs, belonging to the family Varunidae. These crabs are notable for the dense patches of setae ("fur") on their claws, which resemble mittens, especially in the males. The genus includes several species, with the Chinese mitten crab (Eriocheir sinensis) being the most well-known due to its invasive nature outside its native range.

Mitten crabs are catadromous, meaning they live in freshwater for most of their lives but migrate to saltwater to breed. They are native to rivers and estuaries of East Asia, specifically China and Korea. Their life cycle involves migrating upstream into freshwater habitats as juveniles, where they feed and grow. As adults, they migrate downstream to brackish or saltwater environments to reproduce.

The Chinese mitten crab, in particular, has become a significant invasive species in Europe and North America. It is believed to have been introduced through ballast water in ships. Its burrowing activities can cause significant erosion and damage to riverbanks and levees. Furthermore, they can clog water intakes and interfere with fishing gear. Their presence can also disrupt native ecosystems by competing with local species for resources.

Efforts to control the spread of mitten crabs often involve trapping, barrier construction, and public awareness campaigns. Due to their ability to reproduce quickly and adapt to a wide range of environmental conditions, eradication is often difficult to achieve, making containment and management the primary goals. The impact of Eriocheir sinensis highlights the potential ecological and economic consequences of invasive species.