Plankton is a diverse group of organisms that live in the water column and are unable to swim against currents. They include:
* Phytoplankton: Microscopic algae that use photosynthesis to produce their own food.
* Zooplankton: Small animals that eat phytoplankton or other zooplankton.
Some examples of filter feeders that eat plankton include:
* Whales: Baleen whales, like humpbacks and blue whales, have baleen plates in their mouths that filter out krill and other small organisms from the water.
* Fish: Many fish, like herring and anchovies, have gills with fine filaments that trap plankton.
* Mollusks: Some bivalves, like mussels and oysters, use their gills to filter food particles from the water.
* Crustaceans: Krill and barnacles filter food from the water using their legs or other appendages.
So, the answer to your question is plankton.