What are the real effects of oil spill on ocean wildlife?

Oil is one of the most significant materials in the modern world and without it, there wouldn't be many things we have known for years. Nowadays, almost every part of our lives is dependent on oil. Petroleum is used for fuel, heating, plastics, etc. However, not every country has oil, and thus, it needs to be imported. To many places in the world, the only way to get oil is by ships. Nonetheless, transporting oil in gigantic tank barges, can often be dangerous and in case of an oil spill, it could cause immense harm to the ocean’s wildlife and ecosystem. However, most of the oil waste in the ocean consists of oily stormwater drainage from cities and farms, untreated waste disposal from factories and industrial facilities. So, what are the real effects of oil spill on ocean wildlife?