Read the article. Far out in the ocean there is a living clock. It is the fiddler crab, which shows the time of day by the color of its skin. In the daytime, the crab's
skin is dark and at night, the skin is pale. These color changes follow the regular 24-hour rhythm of day and night.
Scientists wanted to find out if the crab was really keeping time or was merely responding to sunlight since it grows darker when light
strikes it. They decided to see what would happen if they kept the crabs in a dark room for several months. Much to their surprise, they discovered
that the crab's skin still changed color, hour by hour, even when no sunlight struck the crab. And stranger still, there was one time of day when the
skin was extra dark. But this event did not happen at the same time every day. It was always 50 minutes later than the previous day. Here was an
important clue to another rhythm that the crab follows-the rhythm of the tides. The moment of darkest skin color is the exact moment of low tide
on the beach where the crab was born.
According to the article, at which moment is the fiddler crab the darkest?