Question: are nematodes protostomes or deuterostomes?
Answer: The two clades diverged about 600 million years ago. Protostomes evolved into over a million species alive today, compared to about 60,000 deuterostome species. Protostomes are divided into the Ecdysozoa, e.g. arthropods, nematodes; the Spiralia, e.g. molluscs, annelids, platyhelminths, and rotifers.