Animal mesoderm forms by enterocoelic pouching, through invagination of the endoderm. The main deuterostome phyla are the Echinodermata and the Chordata. Echinoderms are exclusively marine and include starfish, sea urchins, and sea cucumbers. The chordates are dominated by the vertebrates (animals with backbones), which consist of fishes, amphibians, reptiles, birds, and mammals. The deuterostomes also include the Hemichordata (acorn worms). The Ecdysozoa are protostomes, named after their shared trait of ecdysis, growth by moulting. They include the largest animal phylum, the Arthropoda, which contains insects, spiders, crabs, and their kin. All of these have a body divided into repeating segments, typically
Han Chinese subgroups Han Chinese subgroups The sub groups of the Han Chinese people, also known as Sinitic peoples, Chinese dialect groups or just dialect groups, are defined based on linguistic, cultural, genetic, and regional features. The terminology used in Mandarin to describe the groups is: "minxi" ( // "ethnic lineages"), used in Mainland China, or "zuqun" ( //, "ethnic groups"), used in Taiwan. Other than Hui people, which is a classification for Muslims of all backgrounds, no Han subgroup is recognized as one of People's Republic of China's 56 official minority ethnic groups. Mandarin, also known as the Northern dialects, is the