How do Chinese crabs migrate between fresh water, brackish water, and the sea?

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A herd of wildebeest, including calves, moves across a dusty savanna in Africa with scattered trees visible in the background. — Migration A herd of common wildebeest (*Connochaetes taurinus*) migrating across a dusty savanna in Africa. The animal is a keystone species (i.e., a species with a disproportionately large effect on its biological community) in plains and acacia savanna ecosystems from southeastern Africa to central Kenya.

The Chinese mitten crab (Eriocheir sinensis) is a catadromous species, meaning it spends most of its life in fresh water but migrates to the sea to reproduce.1

During their autumnal spawning migration, these crabs travel from freshwater rivers and streams toward brackish or marine environments, such as bays, to spawn. This life cycle requires them to navigate between different salinity levels, moving from inland waterways into coastal estuaries and the sea to complete their reproductive process.1