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
California spiny lobster lobster is one of the largest spiny lobster species, and grows up to long, but does not usually exceed . Males can weigh up to ., with the record being a 16 lbs., 1 oz. male caught off Catalina island in 1968. The upper side of the animal is brownish red, without the paler bands or spots seen in some other spiny lobsters. The legs are a similar color, but with one or more lighter streaks running along their length. Males and females of all ages can be distinguished by the position of the two round genital openings or gonopores.