The feeding mechanism of Antarcturus and a redescription of A. spinacoronatus Schultz, 1978 (Crustacea: Isopoda: Valvifera)

Abstract

The behaviour and feeding mechanism of valviferan isopods of the genus Antarcturus , exemplified by A. spinacoronatus , have been studied for the first time. This poorly known species is redescribed and details of its morphology, studied by light and scanning electron microscopy, are reported. Adaptations to its special habits include: cuticular spines on trunk segments and limbs which protect it from predators and conceal its outlines; first pereopods with brushes of setae, the most important of which are the medio-ventral and dorsal setae of the propodus used for cleansing the filter combs of pereopods 2-4; long rows of setae on pereopods 2-4 used in passive sieving of phytoplankton; and stout pereopods 5-7 with their spines that are used for climbing. The long setae of the filtering limbs are moved by a hydraulic mechanism. The structure of the basal articulation of these setae is described. The most conspicuous movements of the anterior limbs during feeding are recorded. A comparison with Arcturella sawayae reveals the functional adaptations of the more specialized Arcturella . It is suspected that the family Arcturidae evolved in the Antarctic or Subantarctic Oceans.