Rare Sea Mouse Washes Ashore in Wales, Baffling Beachgoers Before Experts Identify the Unusual Marine Worm

A family beach outing in South Wales turned extraordinary when a spiny creature washed ashore in Oxwich, leaving onlookers puzzled. The animal, initially unidentifiable, was later identified by Swansea University experts as an *Aphrodita aculeata*, or sea mouse. Despite its name, the sea mouse is not a rodent but a marine worm related to earthworms. Its scientific name references the Greek goddess Aphrodite due to its shimmering, iridescent appearance underwater. This glow comes from microscopic bristles that refract light, a phenomenon called pseudobirefringence. While common in UK waters, sea mice typically live at depths of 200 to 3,000 meters, buried in the seabed, where they feed on small invertebrates. Dr. Christopher Lowe, a marine biologist at Swansea University, explained that the worm uses parapodia to burrow and capture prey. The luminescent spines may also serve as a defense mechanism against predators. Finding a sea mouse on the beach is rare, and most specimens are either dead or lethargic. However, when immersed in saltwater, they can regain their vibrant appearance and activity.