Ultrastructure of setae of the maxilliped of the marine planktonic copepod Temora stylifera

Abstract

Copepodid stages and adult females of many calanoid copepods create feeding currents to obtain food. So far it has been uncertain whether food particles were perceived chemically or hydrodynamically or by both modes simultaneously. It was the goal of our study to determine the structures of potential sensors of setae on appendages of calanoids which are involved in the collection of food particles after these have been perceived at a distance from the gathering appendage(s). We report here on the ultrastructure of setae of the maxilliped of adult females of Temora stylifera Dana. This appendage not only contributes significantly to producing the feeding current, but also to gathering actively perceived food particles. Our results indicate that all setae of the female's maxilliped possess structures indicative of mechano- and chemosensors. Since setae of this mostly moving appendage are not still, distance perception of food particles is thought to occur by perceiving dissolved substances. Hydrodynamic sensors of the maxilliped are likely to be utilized when captured food particles have to be manipulated for ingestion or rejection.