Differences in Tolerance to Low-salinity among Red, Blue and Black (Color Pattern) of the Japanese Common Sea Cucumber, Apostichopus japonicus from Ventilation in the Respiratory Tree

Abstract

The differences in tolerance to low-salinity among Red, Blue and Black (color pattern) of the Japanese common sea cucumber, Apostichopus japonicus were examined from the ventilation in the respiratory tree. Red, Blue and Black showed no effect of low-salinity to 30‰, because the ventilation remained almost constant. When the salinity decreased below 30‰, the exhalation and inhalation volume per stroke, and the ventilation volume per min decreased in Red, Blue and Black, though the respiration frequency per min and the inhalation frequency per one cycle of ventilation were similarly almost constant. From these results, it was judged that there was fundamentally no differences among Red, Blue and Black in the ventilation. However, the effect of salinity on ventilation cessation was higher in Red than in Blue or Black.