Common octopus

Photo: Sylvain Le Bris · CC BY-NC

The common octopus is among the most intelligent of Mediterranean invertebrates, demonstrating tool use, problem-solving, and sophisticated camouflage involving both colour and skin texture. At Ile de Riou, octopus dens — identifiable by the piles of empty crab and mussel shells outside — dot the shallower rocky terrain. They are both predator and prey: hunting crustaceans and small fish while being taken by large grouper, moray eels, and conger. Their short lifespan (1 to 2 years) makes population dynamics sensitive to seasonal temperature shifts.