SALT REQUIREMENTS AND SPACE ORIENTATION OF THE LITTORAL ISOPOD LIGIA IN BERMUDA

Abstract

1. Ligia baudiniana moistens its gills by the capillary action of the uropodal spines. 2. The isopod survives best in damp air and is unable to live for long periods in sea water. 3. Changes in the concentration of sea water are detrimental, i.e., Ligia is poikilosmotic. 4. The cations of sea water are toxic in the following order: K > Mg > Ca > Na. K exerts a specific paralyzing effect on the gill movements. 5. On land Ligia orients toward the sea. Positive geotropism appears to be the most important factor.