Protostome Superphyla

Protostome Superphyla is a Browse By group of the Nature Atlas that gathers the two great superphyla of the protostome animals, Ecdysozoa, the moulting animals that include the arthropods and roundworms, and Spiralia, the spiral-cleaving animals that include the molluscs, annelid worms and flatworms. An entry belongs here when its own cited article gives its rank as a superphylum and places it among the protostomes, the animals whose mouth forms first in the embryo. It excludes the deuterostome superphyla, such as the one that holds the chordates. The two clades together hold most of the animal phyla, so the group shows the main split in the protostome branch of the animal family tree.