Spills reaching the shore are dangerous to wildlife. Water birds and mammals become covered in oil, which destroys feathers' water-resistance and the insulation of mammals' fur. Crude oil can poison animals as they try to lick themselves clean. It's not always possible to keep wildlife like birds, otters and walruses away from sea-based oil spills. The consequences of an oil spill linger for decades afterwards. Areas in Alaska affected by the Exxon Valdez spill are still polluted by oil that hasn't biodegraded yet.
