From an ecological perspective, this species behaves like a small aggressive opportunist.
In many European rivers, one small illegal passenger from East Asia quietly gnaws at the banks, clogs pipes, and displaces local wildlife, reports Econews.
The publication notes that the Chinese mitten crab (Eriocheir sinensis) is now so widespread that scientists classify it as one of the most harmful invasive species in the world, with European urban water bodies on the front lines.
According to the article, this crab is easily recognizable because its claws are covered with dense brown "fur," resembling a pair of woolen gloves. It inhabits estuaries around the Yellow Sea, spends most of its life in freshwater rivers, and then moves downstream to brackish water for breeding.
"This lifestyle allows it to inhabit any water bodies—from urban canals to estuaries where active shipping occurs," explains the publication.
Researchers suggest that this crab ended up so far from home due to trade. Larvae and young individuals can cross oceans in ballast water, while adults are transported for food markets and even aquariums.
"Once established, the species quickly spreads through river networks and canals and can even move overland when faced with obstacles such as dams," the publication states.
Moreover, adult crabs tolerate polluted water well, a wide range of temperatures, and varying salinity levels, as noted in the latest ecological risk assessment report.
"In practice, this means that these resilient animals can live without much trouble under an industrial dock, in a suburban drainage ditch, or on a pastoral floodplain," the article states.
What Else Makes It Dangerous
It is noted that the real problem is how these crabs burrow into the ground. They tunnel into soft banks, digging burrows that can reach about half a meter in length.
Interestingly, over time, numerous small holes can weaken dams and canal walls, similar to how termites affect a wooden house.
According to risk assessments, for example, in the Netherlands, burrowing can cause erosion, and in sensitive areas, even bank destruction, threatening flood protection structures and neighboring agricultural lands. The publication shares that engineers notice crabs both in pipes and in silt. In particular, a large number of crabs have appeared at the intake grates of power plants and other facilities along the lower Thames.
Additionally, in the Netherlands, crabs clog equipment at wastewater treatment plants, forcing operators to flush systems more frequently and increasing maintenance costs. Ultimately, this reflects on water bills.
"From an ecological perspective, this species behaves like a small aggressive opportunist. It feeds on algae, aquatic plants, invertebrates, and fish eggs, and then competes with local crabs and crayfish for shelter and food," explains the publication.
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