Imagine yourself observing one of the most diverse ecosystems on earth. Thousands of species of plants and animals provide a dizzying array of color and motion. Massive structures provide a canopy that shelters hundreds of exotic species in a myriad of microclimates. As land-based observers, we almost automatically assume that this is a description of the rich ecosystem of a tropical rainforest. However, if we take ourselves off the safety of dry land and immerse ourselves in the ocean, we will find an equally dynamic environment in the ....