Four-lined Nudibranch (Polycera quadrilineata), White and yellow nudibranch seen grazing on its hydroid food species, St Abbs, Scotland, UK North Sea

underwater four lined nudibranch seaslug seaslugs sea slug sea slugs polycera quadrilineata white yellow nudibranch nudibranches graze grazing eating feeding hydroid st abbs scotland uk united kingdom one animal invertebrate invertebrates coral corals coral reef close up close ups close ups close up north sea sealife sea life