Diverse larval recruitment strategies within the Scyllaridae

Scyllarid lobsters, together with the palinurids, have a long-lived, planktonic phyllosoma larval phase in their early life history followed by a much briefer postlarval phase which at settlement completes the planktonic period of their life cycle. Information on scyllarid larval biology and recruitment mechanisms is fragmentary. Scyllarid species exhibit a wide range of larval recruitment strategies and durations, from entire larval and postlarval phases being completed in just a few weeks within lagoons, through to species that become widely dispersed in ocean basins over many months. In contrast, the phyllosomas of all palinurids so far investigated invariably, over many months, become widely dispersed in the open ocean well beyond the continental shelf. Among scyllarid species a general relationship is apparent between adult size and the extent of larval dispersal. During the planktonic period currents, in combination with larval vertical migratory behaviour, probably play an important role in larval dispersal and return. Although varying greatly in size, the postlarval nisto of most scyllarids appears to be similar in behaviour to the puerulus of palinurids. Nistos are usually (if not always) non-feeding and appear to alternate between swimming at night and resting on the bottom during the day as they move inshore to regain adult grounds before settling and metamorphosing to the first juvenile lobster instar. Those scyllarids with a somewhat abbreviated larval duration and mainly coastal larval distribution-the flat species of Ibacus and Thenus-appear to have succeeded in exploiting local currents and biotic systems to restrict larval dispersal and maintain their place. Based on the characteristics of the larvae and their recruitment mechanisms, there is support for the present division of the Scyllaridae into its four subfamilies, but also backing for revision, particularly of the Ibacinae.