ИСТИНА

My presentation highlights the critical lack of research in hydroid biology and ecology and increasingly disproportionate allocation of scientific effort, resulting in insufficient knowledge about trophic spectra, diets, life spans, growth rates, reproduction requirements, and ecosystem connections for most species. Biodiversity conservation depends on understanding each species' habitat requirements, not simply identifying endangered species and mapping their spatial distribution. 1. Feeding. Hydroids are believed to mostly feed on zooplankton and prey on any animals within a certain size range. We disagree: of the twenty colonial species inhabiting the area of MSU Biological Station on the White Sea, we can only report on the feeding behavior of six species. As for others, we have not been able to establish their trophic spectra, or even what they feed on in principle. Scientific literature does not explain the feeding of most hydrozoans. 2. Species specificity in hydroid predators. Very few species feed on hydroids. We don't have a full list, neither do we know about adaptations to hydroid-based diets, including life cycle adaptations. The role of hydroids in ecosystems remains under-investigated, but is clearly not negligible. 3. Life spans are still unknown for most hydroids. Since a colony is not a community of individuals but an organism in its own right characterized by modular structure, the lack of knowledge about hydroids' longevity is inadmissible. 4. Thermal limits, and especially optimum temperature ranges for hydroids' growth and reproduction are poorly researched. Assumptions have to be made about species specialization based on their actual habitats. 5. Growth rates (for stolons and stems) and duration of hydranth formation are only known for some species. 6. Branching density is an important indicator that has to be included in each species' taxonomic description. 7. “Life cycle” of hydranths. In some species the life span of a hydranth is known to be much shorter than that of the colonial organism (“cormus”). Moreover, new hydranths may emerge in place of resorbed ones. This important method of self-regulation ensures balanced proportions in the structure of a colonial organism. Modern instrumental approaches have expanded research possibilities beyond the use of fixed specimens, and enabled the study of live hydroids.