Marine animals often mistake plastic pollution for food, possibly because of its smell.
Marine grazers such as krill consume microscopic organisms called phytoplankton, which release dimethyl sulfide (DMS). Some of krill's seabird predators, such as petrels and shearwaters, sniff out this chemical to find the grazers. Matthew Savoca and Gabrielle Nevitt at the University of California, Davis, and their colleagues attached beads of the three most common types of ocean plastic to buoys off the coast of California for three weeks. They detected DMS emitted from every seawater-exposed sample, but not from unexposed plastic.
Data from other studies showed that predators that were most responsive to DMS also ingested the most plastic, which can poison animals and block their digestive systems (pictured is an albatross with plastic in its stomach).