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
Starfish to mid 20th century, this species was common along the coasts of the West Indies, but collection and trade have severely reduced its numbers. In the State of Florida, "O. reticulatus" is listed as endangered and its collection is illegal. Nevertheless, it is still sold throughout its range and beyond. A similar phenomenon exists in the Indo-Pacific for species such as "Protoreaster nodosus". With its multiple arms, the starfish provides a popular metaphor for computer networks, companies and software tools. It is also the name of a seabed imaging system and company. Starfish has repeatedly been chosen as a name