Algae traverse the depths of the oceans, either by swimming or changing their density to rise or sink. In the upper layers, they absorb carbon and light to carry out photosynthesis. In the lower layers, they find important nutrients.  

 Instead of changing size and shape, the Manalis lab found that the algae Tetraselmis (seen here) looks the same but grows denser when starving for nutrients to drive its descent to the depths. By shedding light on the role of algae in carbon and nutrient cycles, the discovery may help improve climate modeling.