Freshwater invertebrates including mayflies, stoneflies, water beetles, and freshwater mussels play vital ecological roles and may experience welfare-relevant states that have been almost entirely overlooked.
Freshwater invertebrate welfare sits at the frontier of animal welfare science. Most have simple nervous systems and uncertain sentience, but some - particularly crustaceans like crayfish and signal crayfish - show behaviours consistent with pain and stress. More importantly, the ecological welfare of freshwater systems as a whole depends on healthy invertebrate communities. Protecting these animals through habitat restoration, pollution control, and invasive species management is simultaneously an ecological and welfare imperative.