On the morphology of urosome appendages and their potential function of marine planktonic copepods.

This article focuses on the sensory function of the urosome—the posterior body segment—of planktonic copepods, particularly its setae, in predator detection. It compares the morphology and activity of urosome setae and first antennae (A1) across various developmental stages, noting that juvenile copepods (nauplii) generally have limited posterior sensory structures and rely mainly on A1 for predator perception, while copepodid stages and adults possess more developed urosome setae potentially capable of detecting predators approaching from behind. The study highlights species-specific differences in setae arrangement, length, and movement, suggesting that urosome setae may serve as mechanoreceptors but likely have less sensory capacity than the first antennae. The authors recommend further detailed morphological and behavioral studies to clarify the role of urosome setae in predator recognition among planktonic copepods.