Sand moisture as a factor determining depth of burrowing in the oniscid isopod Tylos granulatus Krauss

ENGLISH ABSTRACT: Tylos granulatus, a sandy-beach isopod, prefers an environmental moisture range exceeding 3,4% but less than 13%. The depths to which the animals burrow are, at least partly, determined by the moisture gradient in the sand. They are, however, incapable of burrowing into totally dry sand. Animals alter their position in the sand in response to changes in moisture content so as to ensure exposure to suitable conditions. ********** AFRIKAANSE OPSOMMING: Tylos granulatus, 'n sandstrand isopod, verkies 'n omgewingsvogtigheidsgraad wat 3,4% oorskry maar minder is as 13%. Die dieptes waartoe die diere grawe word, minstens gedeeltelik, deur die vogtigheidsgradient in die sand bepaal. Hulle is egter nie in staat om in 'n heeltemal dro sand te grawe nie. Die organismes kan hulle posisie in die sand verander met 'n verandering in vogtigheid, om so, blootstelling aan geskikte toestande te verseker.