As the algae spread, one secondary system after another opted to exercise an abundance of caution and close its valves.

随着藻类的扩散，二级系统一个接一个非常谨慎地选择关闭阀门。

When it's dark or the water is murky, however, squid rely on a secondary sensory system, made from thousands of tiny hair cells that are only about twelve microns long and run along their heads and arms.

然而，当天黑或水变暗的时候，乌贼就依赖于二级感官系统，由数千个仅约12微米长的微小毛细胞制成并沿着它们的头和手臂运动。

When it’s dark or the water is murky, however, squid rely on a secondary sensory system, made from thousands of tiny hair cells that are only about twelve microns long and run along their heads and arms.

然而， 当天黑或水浑浊时，鱿鱼依赖次级感觉系统，该系统由数千个仅约 12 微米长的微小毛细胞组成，沿着它们的头部和手臂延伸。