[Contributions to the nutritional and population ecology of Murex trunculus (L. 1767) (Gastropoda, Muricidae), derived from findings at the north coast of Crete (Eastern Mediterranean). With remarks on two species of Naticidae (Gastropoda).] (in G

In early April, 1995, within two weeks all mollusc shells available were collected daily on the beaches of the prevailingly rocky Bali-Bay at the north coast of Crete. Among the 44 marine gastropod species found, Murex trunculus (which was common) was the only "drilling" predator species living and preying at the littoral soil/rock surface. 14 species of Gastropoda, partly zoophagous themselves, and three species of Bivalvia were stated (by analysing the shells) as prey of juvenile and adult M. trunculus. Patella spp., Mitra cornicula and Murex trunculus proved to be the prey species mostly preferred. The rate of cannibalism in M. trunculus amounted to 20% in the location and in the (past) season studied. Basing on additional samples from further sites of the north coast of Crete, three further species of Bivalvia could be stated as prey of three different drilling predators. Barbatia barbata was preyed upon by Thais haemastomo, not by M. trunculus. Among the species living in the sand, lycimeris glycimeris proved to be the prey of Neverita josephina, not of Naticarius hebraeus; in the case of Ctena decussata, this relationship was inverse. So, in the littoral eco-systems, wide interrelationships proved to occur between and within trophic levels. But also specializations were observed, the reasons of which, however, cannot be easily explained.