Franco Banfi / Freshwater jellyfish (Craspedacusta sowerbii) Lake Lugano, Ticino, Switzerland. August. Invasive species.

Juergen Freund / Horned sea stars {Protoreaster nodosus} in shallow water, Indo-Pacific

Tui De Roy / Feral Goat (Capra hircus) herd, new invasion causing rapid desertification of last Giant Galapagos Tortoise stronghold, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Ashley Cooper / Warning sign about the presence of Argentinian mines on the Falkands, February 2014.

Ashley Cooper / Warning sign about the presence of Argentinian mines on the Falkands, February 2014.

Juergen Freund / Invasion of parasitic Waminoa flatworms (Waminoa sp) on soft coral. Misool, Raja Ampat, West Papua, Indonesia.

Juan Carlos Munoz / Memorial statue of Guzman El Bueno, a 13th century fisherman who saved the town from a Moorish invasion, Puerto de Tarifa, Cadiz, Parque Natural del Estrecho, Andalucia, Spain, July 2008

Juan Carlos Munoz / Memorial statue of Guzman El Bueno, a 13th century fisherman who saved the town from a Moorish invasion, Puerto de Tarifa, Cadiz, Parque Natural del Estrecho, Andalucia, Spain, July 2008

Merryn Thomas / Ruins of Signal tower (to warn of Napoleonic invasion) on the deserted island of Great Blasket. Blasket Islands, off the Dingle Peninsula, County Kerry, Republic of Ireland, May 2009.

Adrian Davies / Spanish Bluebell {Hyacinthoides hispanica} in woodland, UK

Will Watson / Invasive Water fern {Azolla fificuloides} covers pond and threatens associated wildlife, UK

Karl Ammann / Ba'Aka pygmy mother and child, Ca,eroon, West Africa. The invasion of traditional forest refuges by logging companies and commercial bushmeat hunters jeopardises the lives of traditional forest-dwelle...