Costes del Maresme

This site features extensive Posidonia meadows. Posidonia, which is often mistaken for an alga, is a phanerogam – a higher plant. It creates some of the most critical ecosystems in the Mediterranean, comparable to forests in terrestrial ecosystems. Posidonia shoots provide nutrients and habitat for many species, including various echinoderms such as sea urchins and starfish. Octopuses and cuttlefish are also present in this ecosystem, alongside other molluscs. Octopuses drill holes in the network of underground Posidonia stems, while cuttlefish mimic the leaves to go unnoticed by predators and prey. They feed on shrimps, crabs, and small fish that live in these forests. Posidonia also attracts many carnivorous and omnivorous fish that feed on crustaceans, molluscs, and marine worms.