Diatoms of this species, sometimes called "commuter" diatoms, remain burrowed in the sand during high tide, and emerge on the sand surface during the daytime low tide.
这种硅藻，有时被称为“通勤硅藻”，在涨潮时留在沙土中，在白天退潮时出现在沙土表面。
2
How did diatoms survive if zinc is so scarce?
如果锌如此缺乏，硅藻是如何生存的呢？
3
Just before the sand is inundated by the rising tide, the diatoms burrow again.