Morphological and physiological adaptations in the marginal sphincter of anemone Phymactis clematis, dana 1849 from different environments

1. 1. We studied the morphology and contractile properties in marginal sphincters isolated from anemones from different environments. 2. 2. Sphincters from specimens from protected areas are ovoid or roughly square shape. Oval sphincters have increased number of mesogloeal branches and the main axis is thickened. Roughly square sphincters have irregular borders, mesogloeal axes of uniform thickness and homogeneous branching. 3. 3. Specimens from exposed areas have sphincters with an ovoid shape and dichotomous branching. 4. 4. Sphincters of specimens from partially protected areas show transition forms. 5. 5. Under stimulation with KCl at different concentrations, sphincters of anemones from exposed environments contract faster and develop higher isometric forces than muscles isolated from specimens of protected areas. 6. 6. It was concluded that sphincters of anemones from different environments have a morphology and a physiological response adapted to the milieu.