Larval molting and growth of the Japanese spiny lobster Panulirus japonicus under laboratory conditions

Ten newly hatched phyllosoma of Panulirus japonicus were cultured individually to monitor body length (BL) and intermolt period, and 2000 were cultured in groups to sample specimens for measurement of body weight. Phyllosoma were fed with Artemia and mussel gonad; the culture seawater temperature was 24–26°C. The individually cultured phyllosoma showed an increment in body length by the first molt of approximately 0.5 mm, and the molt increment increased to approximately 1 mm at 5 mm BL; it was constant to 15 mm BL. The reafter, the molt increment increased exponentially. The duration of the first instar was 6–7 days. Instar duration increased with development up to approximately 2 weeks at the 20th instar (≈16 mm BL) and then became constant. Of the 10 larvae reared individually, five metamorphosed to the puerulus stage. The entire phyllosoma life ranged from 245–326 days (mean 289.0 days), and the number of instars ranged from 22–29 (mean 26.2). Body length in the final instar ranged from 28.50–33.10 mm (mean 30.280 mm). For the phyllosoma cultured in groups, relationships between BL and wet/dry body weights (WW/DW, mg) were expressed as exponential equations: WW=0.0686BL2.2023 and DW=0.0209BL2.1905.