Burrowing Behaviour and Cost in the Sandy-Beach Oniscid Isopod Tylos Granulatus Krauss, 1843

Abstract

AbstractTylos granulatus is an isopod living above the driftline on sandy shores, burrowing to depths of up to a metre or more. Burrowing has been investigated by analyzing video recordings and traces from isotonic and isometric transducers. In crawling, all seven pairs of pereiopods operate in a similar manner and display metachronal rhythm, while in burrowing pereiopods 1 to 3 do the digging, pairs 4 to 6 compact the excavated sand, and pair 7 pushes the bolus behind the animal. Movements of the head also play a significant role in burrowing. Clockwise or anticlockwise partial rotation occurs during burrowing, which takes place in a stepwise progression. With a Burrowing Rate Index of 3, the animal must be considered a powerful burrower, while the energy cost of burrowing is surprisingly low at some 0.3 J m-1.