Reaction of Hydroplasma Movement in the Colony to a Prolonged Thermal Shock and Subsequent Restoration with Optimal Temperature in Dynamena pumila (L., 1758)
摘要
Previously, it was established that the movement of hydroplasma in many hydroid species is not unidirectional, but occurs in the opposite directions in the common tubular body of the colonial organism. Nevertheless, such a pulsatory reversible distribution system is efficient in moving the food particles. We studied the effect of a sharp increase in the environmental temperature and five-day thermal shock on indices of the distribution system functioning in the colonial hydroid. Dynamena pumila: the period and regularity of hydroplasma pulsations, range of movement, growth, pulsations of common body of the colony (coenosarc), etc. After a sharp increase in the temperature of the water (in which the hydroid colonies were kept) by 10°C, the activity of the distribution system (frequency, amplitude of hydroplasma pulsations, and length of flows) increased within several hours, but the growth of colonies already stopped on the second day, and the movements of hydroplasma flows became irregular with significant pauses. On the fifth day of thermal shock, the movement of hydroplasma stopped. Within 24 h after the end of thermal shock, the pulsatory movements of hydroplasma in the stolons resumed and almost returned to normal two days later (except for the extent of food movement throughout the colony). During this time, the growth of colonies had not yet recovered. The reaction of hydroplasma movements in the stolons of D. pumila was superior as compared with morphological indices and growth. Because of this, it becomes possible to determine more accurately and quickly the response of the body to an increase in temperature of the environment.