メバルの胃内容物量と摂餌量との関係

抄録

It has been suggested that the presence of a large caecum in active predaceous swimmers such as Scomber may be correlated with their capacity to attack shoals of fish and to consume large quantites of prey in a short time, In previous papers, the relationship of food intake to the weight of stomach contents was reported on Scomber. In this paper, the relationship above mentioned was examined on Mebaru (Sebastes inermis), which has the stomach of the same kind, but a different mode of life. Sebastes has a large ceacum, too. However, Sebastes is not an active swimmer unlike Scomber but rather a sluggish reef fish.
Food intake rate of Sebastes was smaller than that of Scomber. The maximum weight of the stomach contents in the state of satiety was 6.5-7.5%. The time required for the ingested food materials to be propelled out from the stomach into the intestine varied with water temperature, viz., 70 hours at 14°C, 120 hours at 10°C and 140 hours at 7°C. At a low temperature of 4.5°C, food intake rate was reduced to 1.4% of the body weiget. It was concluded that digestion speed in Sebastes was slower than that in Scomber.
In the state of the complete satiation the length and diameter of the stomach become the maximum; that is, the length of the longitudinal muscular layer of the stomach was 2.1-2.3 times as large as that of empty stomach, while the length of the circular muscular layer extended 2.5-3.0 times. This suggested that the Sebastes stomach is more elastic than the Scomber stomach.