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
Anelida and Arcite Anelida and Arcite Anelida and Arcite is a 357-line English poem by Geoffrey Chaucer. It tells the story of Anelida, queen of Armenia and her wooing by false Arcite from Thebes, Greece. Although relatively short, it is a poem with a complex structure, with an invocation and then the main story. The story is made up of an introduction and a complaint by Anelida which is in turn made up of a proem, a strophe, antistrophe and a conclusion. After the complaint there are a few lines which continue the story, but these may have been added by a later