Editing Filtration (section)

===Filter feeders===
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Filter feeders are organisms that obtain their food by filtering their, generally aquatic, environment. Many of the protozoa are filter feeders using a range of adaptations including rigid spikes of [[protoplasm]] held in the water flow as in the [[suctoria]] to various arrangements of beating [[Cilium|cillia]] to direct particles to the mouth including organisms such as ''Vorticella'' which have a complex ring of cilia which create a vortex in the flow drafting particles into the oral cavity. Similar feeding techniques are used by the [[Rotifera]] and the [[Ectoprocta]]. Many aquatic [[arthropods]] are filter feeders. Some use rhythmical beating of abdominal limbs to create a water current to the mouth whilst the hairs on the legs trap any particle. Others such as some [[Caddisfly#Ecology|caddis flies]] spin fine webs in the water flow to trap particles.