Which one of the following is a filter feeder?

1. A

   Catfish

   Catfish. A predator/scavenger, not a classic filter feeder.

2. B

   Octopus

   Octopus. A hunter.

3. C

   Oyster

   Oyster. Pumps water; filters plankton.

4. D

   Pelican

   Pelican. A scoop-feeder, not a filter bivalve.

Summary. Official key is (c) oyster. Bivalves are textbook filter feeders. Catfish, octopus and pelican take prey other ways.