Circannual Cycle and Oxygen Consumption in Eudendrium glomeratum (Cnidaria, Anthomedusae): Studies on a Shallow Water Population

Abstract. The oxygen consumption of Eudendrium glomeratum was measured monthly, throughout the period of active presence of the species in the field, to obtain indications on its physiological condition in the different phases of the cycle. Sets of one hundred polyps were assayed in the laboratory under normothermic (according to field temperature: 14–19°C) and hyperthermic conditions (22–25°C). The different response to identical temperatures at the extremes of the cycle, together with a differential ability to face stressful conditions in the same periods, suggests that other factors, besides temperature, regulate the seasonal cycle of Eudendrium glomeratum.     

The Ecology of Marine Hydroids and Effects of Environmental factors: A Review

Abstract. The history of the study of hydroid ecology is briefly outlined, pointing out the major methodological innovations which have contributed to the development of ecological research in the last thirty years. The influence of the major ecological factors on hydroid ecology and biology is synthesized, taking into account: substratum, water movement, light, salinity, sedimentation, exposure to air, temperature, food availability and pollution. Besides affecting the species composition of the hydroid community, these factors also influence the morphology and general biology of the individual species. The adaptations and reactions of hydroids to different intensities of the various environmental factors and to their combinations are reported.     

Zonation and Evolution of a Rocky Bottom Hydroid Community*

Abstract. .The distribution in space and time of a hydroid community on a vertical rocky substratum is studied from the surface to 20 m depth. The role of the major environmental factors (light, water movement, temperature) in determining the zonation is evaluated. The results are compared with the main zonation models of Mediterranean benthos. The autecology of the collected species is briefly described.     

Hydrozoa (Cnidaria) symbiotic with Porifera: a review

Many hydroids are symbiotic with other organisms. Sponges, because of their complex canal system and their filter‐feeding activity inducing a continuous water flow, are used by numerous species as either exclusive or facultative substrata. The associated hydroid fauna thriving on or inside sponges shows a wide range of relationships with their hosts. Hydroids may be simply epibiotic on sponges, their stolons running on the host surface. Alternatively, the stolons may grow inside the sponge body, the polyps emerging from the sponge surface, having also the possibility of retraction inside the sponge tissue. Finally, stolons and branches may develop deeply inside the sponge body, producing a skeletal network for sponge growth. This paper reviews the described relationships of hydrozoans symbiotic with sponges and reports new observations.