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

Abstract The goal of this paper is to draw the attention of biological oceanographers to the urosome of zooplankton. The methodology to determine the utilization of urosomes and their sensors for predator recognition is in its infancy. We here describe the potential utilization of setae and their activity of mostly juvenile copepods for the purpose of perceiving predators. Our morphological observations let us assume that calanoid nauplii have few means to perceive predators approaching from the rear and most likely from frontal, as their appendages are moving most of the time. This is being compared to post-nauplii, i.e. copepodid stages, and adults who possess a 2D array of setae on their urosomes, potentially able to perceive predators approaching from the rear. Detailed small-scale observations should reveal the sensor potential of urosomes of nauplii and older stages of planktonic copepods.