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 turtle Spiny turtle The spiny turtle ("Heosemys spinosa") inhabits lowland and hill rainforest, usually in the vicinity of small streams, mainly in hill areas up to 900 m above sea level. The origin of its common and specific name is immediately apparent from the sharp, pointed, spiky-edged carapace, and spiny keel, of this unique turtle, also known as the ‘cog-wheel turtle'. The spiny turtle is known from Brunei, Indonesia, Malaysia, Myanmar, the Philippines, Singapore, and Thailand. Mating behaviour appears to be triggered by rain; in captivity, spraying males with water results in them chasing females and attempting to mount. Nothing is