BURROWING BEHAVIOR AND COST IN THE SANDY-BEACH ONISCID ISOPOD TYLOS-GRANULATUS KRAUSS, 1843

Tylos granulatus is an isopod living above the driftline on sandy shor es, burrowing to depths of up to a metre or more. Burrowing has been i nvestigated by analyzing video recordings and traces from isotonic and isometric transducers. In crawling, all seven pairs of pereiopods ope rate in a similar manner and display metachronal rhythm, while in burr owing pereiopods 1 to 3 do the digging, pairs 4 to 6 compact the excav ated sand, and pair 7 pushes the bolus behind the animal. Movements of the head also play a significant role in burrowing. Clockwise or anti clockwise partial rotation occurs during burrowing, which takes place in a stepwise progression. With a Burrowing Rate Index of 3, the anima l must be considered a powerful burrower, while the energy cost of bur rowing is surprisingly low at some 0.3 J m(-1).