Integral effect of a non-centralized biosystem parts interaction with the example of major hydroplasma flow formation in the shoots of colonial hydroid <i>Dynamena pumila</i> (L., 1758)

Abstract

The emergence of the main hydroplasmic flows (HFs) in the shoot of colonial hydroids (Hydrozoa), flowing from it into the stolon and capable of transporting food particles along stolons to the opposite end of the non-centralized organism, is described. We developed a simple method for minute-by-minute visual registration of the direction of particles movement in hydroplasm in each shoot shaft module for 1.5 hours. The HFs entering the shoot are shown to be rhythmic (15.1 ± 5.0 min), but if the outgoing HFs are usually filled with food particles, the returning HFs, as a rule, contain few particles. There is more chaos in the pulsations of hydrants on the shoot than in the stem of the shoot, i.e. the period of receipt of HF from hydrants to the stem of the shoot varies significantly. Previously, it has been assumed that outgoing HFs are formed only under the influence of incoming ones, as a response to coenosarc stretching when hydroplasma enters the shoot (under the pressure of other pulsators in the colonial organism). However, it turned out that from the appearance of the incoming to the beginning of the outgoing HF, 5 minutes elapsed as an average. During this time, hydroplasma fills not only the stem of the shoot, but also the hydrants, which contract in response, although not simultaneously. The hydrants squeeze out the hydroplasma during compression into the stem of the shoot, after which the coenosarc of the shoot begins to shrink. It turned out that when taking into account the pulsations of hydrants for 3 minutes, a clear periodicity is registered, coinciding with the periodicity of HF emanating from the shoot, resulting from compression of the coenosarc of the stem. At the same time, hydroplasma cannot enter the hydrants until the end of the long phase of their compression. Otherwise, the movements of the hydroplasma would be limited only by the escape space. Thus, in a non-centralized system such as colonial hydroids organism, the coordination of pulsations of hydrants and coenosarc occurs with significant backlash. In the coenosarc, as a whole, the pulsations are rhythmic with minor fluctuations, while the hydrants are sources of many little rhythmic pulsations (with large variations in the period).Therefore, the contribution of hydrants to the formation of the main HF does not appear at once, but for several minutes in the interval between the incoming and outgoing flows.