FREE INSTITUTE OF SCIENCE 
ON THE LIFE HISTORY OF AN ECONOMIC CUTTLEFISH OF JAPAN 
FOOD 
The chief method of catching is by angling. The implements vary 
according to different localities, but the squid jig is the most universally used 
(fig. 2). The jig is pulled through the water, so that it resembles a rapidly 
swimming fish. This feature of the fishing stands in close 
relation to the natural food, on which the animal lives. I 
have examined the contents in the stomach of about 250 
grown individuals from various localities. Of the contents 
examined, about 70 % consisted of fishes, 20 % of cuttle- 
fishes, and the remaining 10 % of crustaceans and others. 
The species determination of these was of course by no 
means easy, because they were greatly mangled and so well 
digested that only their hard parts were left. The size of the 
food animals was, therefore, likewise not easy to be deter- 
mined, but we may roughly infer it from the size of the jig 
which the animal likes to take, which varies, as is well 
known, from 60 mm. to 100 mm. in length. The fishermen, 
who are well aware of what size is best suited for the cuttle- 
fish at a given period, use larger jigs as the fishing season 
proceeds. In some places fishermen use a larger anchor- 
shaped hook, through the stalk of which a grown mackerel is 
put as bait. When the cuttlefish are closely crowded, fisher- 
men can draw up three or four of them together. This sug- 
gests that the cuttlefish may attack fishes larger than them- Sand ueaee 
selves, : ee 
In younger individuals below 85 mm. in mantle length, ae a oe 
the natural food is quite different from that of the adult so mae et ro = 
far as my examinations show. It consists of smaller floating _ piece made of bone 
organisms and among these microcrustaceans predominate. ee nde ook 
Fic. 2. 
RATE OF GROWTH 
With the material so far examined it has not been possible to determine 
the exact age of maturation and the duration of life. The anatomical structures 
I have examined do not furnish any index of the age of the cuttlefish as do the 
scale and otolith of ordinary fishes, by means of which the annual rate of growth 
