Ecological Studies of Turbo cornutus Solander-1. Changes of the Spines on the Shell due to Environments

Abstract

As shown in Fig. 1, the spines on the dorsal surface of the Japanese topshell, Turbo cornutus, a~e usually divided into four types according to their position. In June 1949 the writer liberated-158 topshells into an artificial pool 15mx7m wide in Kominato Marine Biological Laboratory, Chiba prefecture. Here the environment, from the standpoint of salinity, current, bottom-character and available food, was not as suitable for this species as was its natural habitat. In June 1950, 58 specimens were recollected from the pool. Observing their spines, it was found that peculiar changes had occurred daring the year of transplantation into the artificial pool, as-shown in Tables 1 and 2. The groups produced shell spines that lower in position (AB, AC. and 0C) are proved to be superior in increased weight and length of shell (Tables 3 and 4). This phenomenon shows the difference in physiological action between the upper and lower spines, the upper spine being related to excurrent action, the lower to incurrent action. Anatomical observations on this snail (Fig. 2) and on the parasitic gastropod, Amalthea conica (Table 5). bear out this conclusion. © 1953, The Japanese Society of Fisheries Science. All rights reserved.