Motion behavior of nauplii and early copepodid stages of marine planktonic copepods

The goal of this study was to quantify periods of activity and velocities of late naupliar and early copepodid stages of planktonic copepods occurring regularly on the southeastern continental shelf of the USA. We obtained quantitative information on eight species, including adult females of Oithona plumifera. All studies were conducted at food concentrations near or above satiation levels. Activities ranged from 0.85% (adult females of O.plumifera) to 100% of time (nauplii and copepodids of various calanoid species). Motion velocities (excluding escape motion) covered more than one order of magnitude: from 0.39 mm s~' for nauplii of Temora stylifera to 5.24 mm r 1 for nauplii of Oncata meditenanea. Ranges of activities of species range from occasional for early juveniles to adult females of O.plumifera to 100% for the same range of T.stylifera, the latter creating a feeding current from N in onwards, the former not at all. Of notable interest is Centropages velificanis which moves intermittently as a late nauplius, continuously as an early copepodid and intermittently as an adult All observed calanoid late nauplii and copepodids move in three dimensions, excluding copepodids of the shelfbreak/oceanic Paracalanus oculeatus. The results indicate not only significant differences in motion behavior between cyclopoids and calanoids, but also between calanoid species. Yet, some calanoid species show little ontogenetic changes at all.