魚類稚仔期の口径に関する研究-III

Abstract

In the previous paper, it was reported that a marked inflection occurs in the ratio of the upper jaw length to total length accompanying the growth of larval marine fishes. However, the meaning of the phenomenon is not explained. In the present paper, in order to clarify the biological significance of the inflection, Lateolabrax japonicus and Pagrus major were selected, because morphological, physiological and ecological studies in the larval stage of these fishes are advanced. The knowledge on the formation of fin rays, development of alimentary canal, change of feeding habit etc. in the larval stage of these species were compared respectively with total length at the inflection point obtained from the relation between the upper jaw length as a percentage of total length and total length of fish. The results obtained are as follows: 1) It was noticed that the period of completion of fin rays and of digestive organs in the larval stage is shown by the total length at the inflection point. 2) The transitional period from post-larvae to juveniles could be shown by the total length at the inflection point.