CALCIUM ACCUMULATION DURING THE TRANSITION FROM PUERULUS TO JUVENILE IN THE WESTERN ROCK LOBSTER, PANULIRUS-CYGNUS (DECAPODA, PALINURIDAE)

Dry weight in P. cygnus increases from 58.4 +/- 5.4 mg in pueruli to 8 8.5 +/- 11.9 mg in first-moult juveniles. Changes in ash-free dry weig ht, from 51.2 +/- 4.9 mg in pueruli to 56.7 +/- 9.5 mg in first-moult juveniles, are insufficient for the increase in dry weight to be attri butable to accumulation of organic matter, The ash weight increased su bstantially after ecdysis of the puerulus (6.9 +/- 2.3 mg for pueruli; 31.9 +/- 2.8 mg for first-moult juveniles). This change may be attrib uted to the process of mineralization, which involves accumulation of calcium salts, and other mineral salts, as well as a range of organic components. Calcium contents, measured with flame emission, increased from 0.46 +/- 0.06 mg in pueruli to 1.59 +/- 0.26 mg in first-moult ju veniles. Histological studies showed substantial calcium deposits in t he gastric mill and mouth region of the juvenile but not of the post-s ettlement puerulus. Since internal calcium reserves are small in the p uerulus, calcium may initially be taken up directly from the sea water following ecdysis.