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Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. Filter feeding is one of the four major types of feeding. Some animals that use this method of feeding are clams, krill, flamingos, sponges and whale sharks.

Krill feeding under high phytoplankton concentration. A slow motion movie (slowed down by a factor of 12; 490kB) is also available.

The Antarctic krill manages to directly utilize the minute phytoplankton cells, which no other higher animal of krill size can do. This is accomplished through filter feeding, using the krill's developed front legs, providing for a very efficient filtering apparatus:^[1] the six thoracopods form a very effective "feeding basket" used to collect phytoplankton from the open water. In the movie linked to the right, the krill is hovering at a 55° angle on the spot. In lower food concentrations, the feeding basket is pushed through the excellent water for over half a meter in an opened position, and then the algae are combed to the mouth opening with special setae on the inner side of the thoracopods.

Click on the images for higher resolutions.

high resolution in situ image of an undulating life Aurelia in the Baltic Sea showing the grid of the fibres which are slowly pulled through the water. The motion is so slow that copepods can not sense it and don't react with an escape response

higher magnification showing a prey item, probably a copepod

The prey is then drawn to the body by contracting the fibres in a corkscrew fashion (image taken with an ecoSCOPE

Filter basket of a mysid.

These 3 cm long animals live close to shore and hover above the sea floor, constantly collecting particles. They are an important food source for herring, cod, flounder, striped bass. In polluted areas they have in their tissue extremely high toxin levels, they are very robust and take a lot of poison before they die. Such filter feeding organisms are the reason that much of the materials we throw in the oceans comes back to us in our food.

• Particle

Contrast with:

• Deposit feeders
• Fluid feeders
• Food-mass feeders

1. ^ Kils, U.: Swimming and feeding of Antarctic Krill, Euphausia superba - some outstanding energetics and dynamics - some unique morphological details. In Berichte zur Polarforschung, Alfred Wegener Institute for Polar and Marine Research, Special Issue 4 (1983): "On the biology of Krill Euphausia superba", Proceedings of the Seminar and Report of Krill Ecology Group, Editor S. B. Schnack, 130-155 and title page image.

• Filter feeder of krill