Chemotactic Turning Behaviour of Tubularia Spermatozoa

Chemotaxis of spermatozoa to female gonophores has been shown to occur in Campanularia, Tubularia and other hydroids (Miller, 1966 a, b). Cinemicrographic records of the movements of Campanularia spermatozoa in the vicinity of female gonophores or of glass capillary pipettes containing extracts of female hydranths have shown that chemotactic aggregation of the spermatozoa occurs because the spermatozoa turn and swim toward the source of chemotactic stimulation (Miller, 1966 a). In the present paper the turning behaviour of hydroid spermatozoa during chemotaxis is examined in greater detail, using multiple-exposure dark-field photomicrography under conditions where the spermatozoa are swimming at an interface between sea water and a glass surface. Under these conditions the changes in bending behaviour of the sperm flagellum can be photographed, in addition to the changes in the path of the spermatozoon. Although this report deals exclusively with spermatozoa of Tubularia, similar results have been obtained from less extensive attempts to photograph the turning behaviour of Campanularia spermatozoa.