Complex sentence: Many invertebrate taxa have a greater number and variety of species than the entire subphylum of Vertebrata and some of the so-called invertebrates, such as the Chaetognatha, Hemichordata, Tunicata and Cephalochordata are more closely related to the vertebrates than to other invertebrates.
Split into simpler sentences: Many invertebrate taxa have a greater number and variety of species than the entire subphylum of Vertebrata. Some of the so-called invertebrates, such as the Chaetognatha, Hemichordata, Tunicata and Cephalochordata are more closely related to the vertebrates than to other invertebrates.