Buccal cirri are feeding structures found in the oral hood of primitive jawless organisms called amphioxus.
The presence of external particles can be detected by an organism possessing buccal cirri due to the sensory abilities associated with the mechanoreceptors.
Food and fluid particles passing through buccal cirri are sorted using chemoreceptors, which respond to chemical stimuli.
[6] Buccal cirri function as a food processing organ that is used to prevent larger particles from entering the oral hood.
[7] The buccal cirri does this by working with the velar tentacles to create a comb like feeding appendage that sifts the particles that are entering via the water stream.