This interactive tree diagram visualizes a hierarchical animal classification system, with branching categories like vertebrates and invertebrates expanding into specific classes such as mammals, birds, and arthropods. The visualization uses an animated SVG layout via D3 version 3.5, where nodes can be clicked to collapse or expand child branches. Node colors are determined by level—black for the root, pink for major divisions, brown for subgroups, and green for leaf species—while the data is embedded directly in the code as a JSON-style array. The implementation relies on `d3.layout.tree` and `d3.svg.diagonal` to render the curved links and responsive structure.