This example visualizes a hierarchical tree of animal species, branching from a top-level root into vertebrates and invertebrates, then further into specific groups like birds, fishes, mammals, and insects. It uses D3.js version 3.5 with the `d3.layout.tree` API to compute node positions and `d3.svg.diagonal` to draw curved links between parent and child nodes. Node shapes are rendered as SVG symbols via `d3.svg.symbol`, with red diamonds for values greater than or equal to nine and red circles otherwise, while link colors reflect each target’s level property. The chart is built in React and rendered as inline SVG on an HTML page.