Susanne Kühn and Jan van Franeker at Wageningen Marine Research reviewed every published record of marine animals ingesting or becoming entangled in debris, updating earlier counts from 1997 and 2015.
They found 914 marine species affected: 701 species with recorded ingestion and 354 with entanglement (some both). The total has grown from 267 species in 1997 to 557 in 2015 and 914 in 2020, largely because more species are being studied. Affected groups include all seven turtle species, more than half of marine mammal species and hundreds of fish, seabird and invertebrate species.
The review matters because it is the reference count that campaigners and policymakers cite for 'species harmed by plastic', and it shows the number keeps rising as researchers look.
A species being recorded once does not mean every individual is affected; the count reflects research effort as well as exposure.