Sun seekers are being warned to stay vigilant to avoid being stung by weever fish. The aquatic creatures are difficult to see because they hide themselves in sand. The species, which are mostly brown and around four to eight inches long, have been reported on beaches across the UK such as in Wales, Kent, Plymouth and Cornwall. Weever fish carry a potent venom in protective spines on their dorsal fins and gill covers which is released if someone is unlucky enough to stand on them.