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
Spiny mouse organism to study menstruation and reproductive disorders, as Mus musculus, the common laboratory mouse, does not menstruate. At least two species of African spiny mice, "Acomys kempi" and "Acomys percivali", are capable of autotomic release of skin upon being captured by a predator. They are the only mammals known to do so. They can completely regenerate the autotomically released or otherwise damaged skin tissue - regrowing hair follicles, skin, sweat glands, fur and cartilage with little or no scarring. It is believed that the corresponding regeneration genes could also function in humans. In a research article published on May 16,