These plastic items are the deadliest for marine species and birds Plastic in the ocean is eaten by over 700 species, but just a few items are responsible for the most deaths. Representational image. | AFP How do we save whales and other marine animals from plastic in the ocean? Our new review shows reducing plastic pollution can prevent the deaths of beloved marine species. Over 700 marine species, including half of the world’s cetaceans (such as whales and dolphins), all of its sea turtles and a third of its seabirds, are known to ingest plastic. When animals eat plastic, it can block their digestive system, causing a long, slow death from starvation. Sharp pieces of plastic can also pierce the gut wall, causing infection and sometimes death. As little as one piece of ingested plastic can kill an animal.