This interactive tree diagram visualizes a biological classification hierarchy, showing how animals are grouped into vertebrates and invertebrates, with further subdivisions down to individual species. The visualization uses a collapsible tree layout where nodes can be clicked to expand or collapse their children. Built with D3.js v3 and React, the code employs `d3.layout.tree` for the hierarchical layout, `d3.svg.diagonal` for the orange curved links, and SVG circles and text for nodes. Colors distinguish different taxonomic levels, with yellow nodes, green type indicators, and black leaf nodes.