Salema porgy

Photo: Guido and Carrara family · CC BY

Sarpa salpa is the primary grazer of Posidonia meadows across the Mediterranean, forming dense shoals of several hundred fish that move methodically through the seagrass canopy, clipping leaf tips and fertilising the meadow with their excretion. At Steno the current narrows concentrate salema schools into dense silver columns visible from the surface, and the channel walls are peppered with the characteristic bite marks of their scrapers on algae-crusted rock. The species has an unusual secondary metabolism that can cause vivid hallucinogenic experiences if consumed — an ethnobotanical quirk referenced since antiquity in texts from the Crete region.