A person or creature that gapes; a type of shellfish (clam) that cannot close its shell completely.
From 'gape' plus the agent suffix '-er,' creating a noun for something that gapers. In zoology, it specifically refers to bivalves in the family Tresidae that have gaping shells.
Gaper clams are defensive specialists—they evolved their gaping shell because they live in permanent burrows where closing completely is impossible, so they embraced their limitation as a way of life.
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