Ka-pow! If phytoplankton could make noise, this is what they might sound like off the coast of France this spring. These two satellite images show a bloom of the microscopic plants in the Bay of Biscay on April 20 and then (wham!) on May 4. A third image is available here.
The explosive burst of phytoplankton was triggered by two things: food and sunlight. The food comes in the form of nutrient-rich freshwater form the land, and the sunlight just comes with the season.
Larger Than Life: Photos
The downside to this sort of population explosion is that while it provides food for everything from zooplankton to whales, it can sometimes also cause the water to be starved of oxygen, which is not good if you are a fish or other oxygen dependent creature who does not breathe air.
NASA's Terra and Aqua satellites captured these images using their Moderate Resolution Imaging Spectroradiometers.