Preferences of the Common Octopus Octopus vulgaris Cuvier, 1797 (Cephalopoda: Octopodidae) to Artificial Nests Placed in Different Habitats at Urla Islands, Aegean Sea, Turkey

摘要

The common octopus Octopus vulgaris Cuvier, 1797 exhibits specific building den characteristics. This specific sheltering behaviour is a factor affecting distribution and abundances of octopuses in the marine environment. Based on this, the preference of octopuses to natural dens and artificial nests located in two habitats, i.e. sea-grass meadows of Neptune grass Posidonia oceanica (L.) Delile and sandy bottom areas, was determined. Totally, 200 artificial nests were placed along shores of Urla Islands, Aegean Sea, and observed through three years. During the study, a total of 245 octopuses were observed and 107 of them (43.67%) inhabited natural dens while 138 were found in artificial nests (56.33%). For those from artificial nests, octopuses preferred Neptune grass habitats (66.33%) and only 33.33% of individuals gave a preference to sandy areas. In the case of natural dens, these rates were 52.34% for Neptune grass meadows and 47.66% for sandy habitats. These results indicate that Neptune grass areas are preferred by octopuses in terms of using artificial nests with higher ratio.