Abstract
A leaflike shrimp Nebalia sp., which belongs to the most primitive genus of Malacostraca, has been found abundantly at the base of Bryopsis sp. growing in an outdoor concrete tank used for Homarus culture at Sanriku. The species is considered to be desirable as a living food organism for larval rearing because of its suitable size and tolerance to deterioration of the bottom condition.
Sampling was done in the pond from July to December of 1983. Water temperature ranged from 22.3°C in summer to 4.5°C in winter. The animals were found throughout the season with the highest occurrence of egg-bearing females in October. The larvae were reared successfully at water temperature between 15°C to 25°C in combination with the salinity between 20‰ to 33‰ under the continuous darkness. The larvae showed the best growth at 25°C in combination with 33‰. The most effective food for the larval rearing in the laboratory was the fine particles of the dried food as shrimp pellet and krill.
The larvae hatched out as adult form. Number of segments in the flagellum branches of the first antenna and the second antenna increased from 3:3, expressed as segmentation formula, at I stage to 4:3, 5:4, 6:5, 7:6 and 8:7 at II, III, IV, V and VI stages, respectively. After VII stage, the increase became irregular.
