Chaeta

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A chaeta or cheta (see spelling differences) is a chitinous bristle or seta found on annelid worms such as the earthworm, although the term is also frequently used to describe similar structures in other invertebrates. The plural form is chaetae or chetae.

In the Polychaeta, they are located on the parapodia. They consist of two sets in Hediste diversicolor (=Nereis diversicolor), one below the dorsal cirrus on the notopodium and another above the ventral cirrus on the neuropodium.