The pharaoh cuttlefish Sepia pharaonis
Ehrenberg, 1831, is one of the most important
species exploited along the Eastern Arabian
Sea. A study on the relationships between
dorsal mantle length (DML) and number of
cuttlebone septa (or chambers) and between
total body weight and number of cuttlebone
septa were carried out in S. pharaonis collected
from the south-eastern Arabian Sea. The
cuttlefish samples were collected from Cochin
Fisheries Harbour (133 males and 67 females).
Dorsal mantle length-at-chamber count and
weight-at-chamber count were statistically
higher in males than in females. The available
literature suggests that females of S. pharaonis
are heavier than males while males are found
to attain greater ultimate lengths throughout
the lifecycle. Literature also suggests that the
rate of cuttlebone septum formation is the
same in both sexes of Sepia species, however
in the present study, S. pharaonis males have
slightly higher growth rates than females
(Fig. 1 & 2). The study indicates that there is
considerable scope to use cuttlebone chamber
counts as a means of determining actual age
of cuttlefishe