Uncommon pelagic and deep-sea cephalopods in the Mediterranean: new data and literature review

Abstract

Compared to their shelf-living relatives, the biology and ecology of most pelagic and deep-sea cephalopods is currently rather unknown owing to the difficulties to catch them. To cover the lack of information on these cephalopods, scientists have to make use of the limited and fragmentary data gathered from different sources such as sporadic captures, strandings or stomach contents of their predators. Here, we give some biological and ecological information on eleven uncommon pelagic and deep-sea cephalopods collected during more than fifteen years of fisheries surveys in the western Mediterranean Sea. The cephalopods investigated include two epipelagic octopuses (Ocythoe tuberculata and Tremoctopus violaceus), one deep-sea cirrate octopus (Opisthoteuthis calypso), the sepiolid Stoloteuthis leucoptera and seven teuthoid species inhabiting preferentially mesopelagic and bathypelagic waters (Abraliopsis morisii, Ancistrocheirus lesueurii, Brachioteuthis riisei, Chiroteuthis veranyi, Chtenopteryx sicula, Onychoteuthis banksii and Taonius pavo). Although all of these species are either cosmopolitan or present a wide distribution in other oceans, they are nevertheless relatively rare in catches, and therefore remain poorly known. The finding of T. pavo represents the first record of this cephalopod in the Mediterranean.