With the geological closure of the Isthmus of Panama 4 million years ago, the two largest oceans of the planet were separated, causing their respective marine populations to become divided. Central America was gradually formed by the intense volcanic activity of the area, and began to be colonized by plants, birds and bats capable of invading every new island in construction. The highest mountains in Central America, some unique ecological conditions and the erosion produced by violent tropical storms finally gave shape to the "Great Bridge" uniting the Americas. Across the bridge, the journey of thousands of pioneering species begins.