Could the current Animal Kingdom phylogenetic tree change? ‘Enigmatic animals’ predicts that it will not, but that new phyla may be discovered in the remote areas of the deep sea and tropical rainforests where investigations have just scratched the surface, or that reclassification of certain animals may result in phyla being created or deleted. The phylogenetic tree is a starting point for biological investigation. It provides a framework that allows careful and rigorous interpretation of biological data. With the robust framework of a phylogenetic tree we can compare anatomy, physiology, behaviour, ecology, and development between animal species in a way that gives insight into the pattern and process of biological evolution.