Acicula

This article is about a bristle-worm anatomical feature. For the snail of Aciculidae family, see Acicula (gastropod).

Acicula (sg.: aciculum) are strong, stout internal chaetae that provide support to parapodia in polychaete annelids.

File:Arctonoe sp. parapodium with chaetae labels.png

Microscope photograph of a parapodium from a specimen of Arctonoe sp. showing the internal acicula that support the two lobes of the parapodium.