Invasion of the Body Snatchers

Brown sea squirts formally known as tunicates, from the genus Didemnum attach themselves to a rock on a beach in Sandwich, Mass. WHOI research associate Mary Carman and colleagues have been studying the invasive, filter-feeding species and trying to figure out how to keep it from crowding out other life in coastal waters. This species spreads up from the bottom of rocks as it grows, covering everything in its path, including vegetation and shellfish. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)