The remaining ecological zones, with their progression from shoreline to climax forest, are a classic illustration of the concept of ecological succession. Much of this progression is due to the changing nature of Presque Isle and its shifting shoreline and dunes. The shoreline, the second zone, is formed by wave action and is in equilibrium between erosion and deposition, with the initial plants stabilizing the sand of the new shoreline. The newly formed sandy plain and the ponds formed in it are the third zone. The ponds start as trapped pockets of lake water and can erode away or be filled by wind-blown sand or drifting dunes. The new ponds provide habitat for plants and animals: for example, the state park is home to 89 species of Odonata (dragonflies and damselflies) and Lepidoptera, including 35 different butterflies, as well as 84 different sorts of spiders.