Evolution of life cycles, including migration, in spiny lobsters (Palinuridae)

A comparison of the documented ecology and behaviour of the separate phases in the life cycles is presented. Data gathered during the review show that during the evolution of the family from deeper-water habitats to the more rapidly fluctuating shallower waters, there have been many biological adjustments at each phase in their life cycles. In the more ancient Stridentes genera, like Puerulus, the larvae are found well below the surface waters and the pueruli often settle at greater depths than those of the adults. Long incubation times, few larval instars, and year-round spawning are probably their life cycle characteristics. As an intermediate-evolved genus of Stridentes, Palinurus lives along the outer shelf, grows slowly, matures late, and breeds seasonally once a year. Incubation time is long, the larvae live at depth, the number of larval instars is limited, and the puerulus is a weak swimmer. Settlement is often downstream of the breeding stock. Incubation times are short for the more recently evolved Stridentes Panulirus, the larvae pass through many instars in the surface waters to c. 200 in. Some pueruli settle in special coastal habitats, others settle in the same habitat as the adult. Breeding in the cooler water First Major Lineage species is seasonal, one or two broods being produced. Most of the species in the tropical Second Major Lineage are faster growing, breed repetitively over a long breeding season, and have a shorter larval life. For the Silentes, the trend in biological changes from deep to shallower water is comparable with that of Stridentes. Incubation is probably long in the more ancient Projasus, the larvae are rare in surface waters and the pueruli settle at depths similar to those of the adults. Sagmariasus and Jasus breed once during a defined season, incubation time is moderate, and the larvae pass through many instars. The pueruli of Sagmariasus settle downstream and exhibit contranatant migration whereas the pueruli of Jasus swim strongly to their shallow habitats. In each life cycle phase, migration methods range from vertical paddling in phyllosomata, horizontal swimming in pueruli, and horizontal walking when juveniles move to adult habitats. Adult movements are associated with foraging, searching for shelter, avoiding adverse seasonal conditions, or walking to preferred offshore locations for moulting and reproduction.