Fabio Pupin / Red swamp crayfish (Procambarus clarcki), invasive species, captive, Italy, July.

Remi Masson / European crayfish (Astacus astacus) in a lake. Alps, Switzerland, July.

Linda Pitkin / 2020VISION / Fisheries assistant Stephanie Kershaw and volunteer John Dumont from the Eden Rivers Trust searching for White clawed crayfish (Austropotamobius pallipes) as part of a capture and release conservation...

Linda Pitkin / 2020VISION / White clawed crayfish (Austropotamobius pallipes) on river bed, viewed underwater, River Leith, Cumbria, England, UK, September 2012.

Linda Pitkin / 2020VISION / White clawed crayfish (Austropotamobius pallipes) underwater on riverbed, showing defensive posture, River Leith, Cumbria, England, UK, September 2012. Did you know? White clawed crayfish can live fo...

Linda Pitkin / 2020VISION / White clawed crayfish (Austropotamobius pallipes) underwater on riverbed, River Leith, Cumbria, England, UK, September 2012.

Rob Jordan / 2020VISION / Signal crayfish (Pacifastacus leniusculus) in a defensive posture after being caught by The Tweed Foundation monitoring the species population and spread on the River Till, Northumberland, England, UK...

Rob Jordan / 2020VISION / Signal crayfish (Pacifastacus leniusculus) in a defensive posture after being caught by The Tweed Foundation monitoring the species population and spread on the River Till, Northumberland, England, UK...

Michel Roggo / Signal crayfish (Pacifastacus leniusculus) Europe, introduced from North America

Paul Hobson / Signal Crayfish {Pacifastacus leniusculus} Leicestershire, UK

Andy Sands / Signal Crayfish (Pacifastacus leniusculus) defence posture in chalk stream, Hertfordshire, UK

Dietmar Nill / Louisiana swamp crayfish, Germany