Test shape in Amphistegina spp. grown in culture is influenced by light availability and water motion. Saturation light level for A. gibbosu was between 6 and 14 μE/s m2; growth rates at 14 and 40 μE/s m2 were 5.9%/d and thickness-to-diameter (T/D) ratios were 0.36. At reduced light levels, growth r...