Hemolymph osmoregulation in several myriapods and arachnids

Abstract

1. 1. Osmotic responses to dehydration and rehydration were examined in a millipede, Cylindroiulus londinensis (Leach), a centipede, Lithobius fotficatus L., a harvestman, Leiobunum vittatum (Say) and a spider, Argiope trifasciata (Forskal). 2. 2. Osmoregulatory responses to dehydration, assessed using a graphical method, differed considerably between species. Male millipedes regulated hemolymph osmolality better than females. 3. 3. Size and temperature influenced water content and hemolymph osmolality in millipedes. 4. 4. Rectal fluid became hyperosmotic to the hemolymph in dehydrated harvestmen.