Filter feeder
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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.
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[edit] Filter feeding in krill
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 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.
[edit] Details of the feeding basket
Click on the images for higher resolutions.
 The filter formed by the thoracopods. The long comb like setae stretch outwards to cover over the gap between the thoracopods |
 The first order filter setae have attached to them second order setae. The second order setae are aligned in rows, these rows form a v-shape. The v shape of the setae align towards the inside of the feeding basket. (electron microscope image). To display the total area of this fascinating structure one would have to reproduce this tile7500 times. |
 Third order setae form further rows which reduce the gap between the second order setae. This produces a net like structure. In some parts of this structure the gaps between third order setae are only 1 micrometer wide (electron microscope image). |
[edit] Filter feeding in Moon Jelly
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 |
[edit] Filter feeding in mysids
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.
[edit] See also
Contrast with:
[edit] References
- ^ 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.
[edit] External links
Alfred Paseika/ Photo Researchers
