Identification guide for cephalopod paralarvae from the Mediterranean Sea

Cephalopods are key components of marine trophic webs, where they constitute major food resources for a large variety of predators including fish, other cephalopods, marine mammals, and seabirds (e.g. Clarke, 1996; Piatkowski et al., 2001; Cherel et al., 2009). Cephalopods are, in turn, voracious predators of fish and crustaceans (Boyle and Rodhouse, 2005). Octopuses, squid, and cuttlefish are also important living marine resources, maintaining relevant fisheries around the world (FAO, 2012). Despite their economic and ecological importance, the number of studies on these molluscs, until relatively recently, has been small compared to other taxonomic groups such as fish, crustaceans, or marine mammals (Piatkowski et al., 2001). The lack of knowledge is even worse in the case of larval stages, which have been little studied worldwide and represent, without doubt, a challenge for future studies on cephalopods. The difficulties in sampling (low abundance and patchy distribution), the uncertainties of species identification, and problems related to their maintenance in captivity are major limitations to those studies (Vecchione, 1987; Boyle and Rodhouse, 2005). The taxonomy is probably the biggest obstacle to overcome, since the identification of virtually all larval and juvenile stages of cephalopods has been, and still is in many cases, confusing and problematic (Sweeney et al., 1992).