Bladder wrack and other seaweeds washed up on a shoreline. Four species are present: bladder wrack (Fucus vesiculosus, centre); serrated wrack (Fucus serratus, behind the bladder wrack); channelled wrack (Pelvetia canaliculata, left); and knotted wrack (Ascophyllum nodosum, right). Seaweed is a marine alga, some species of which float freely in the sea while others remain attached to the shore. Photographed in November, on the Isle of Skye, off the coast of Scotland.