The bee hummingbird, the smallest living bird, weighs less than 2 grams, and the goby fish of the Philippines and the Cuban tree frog are less than 1/2 of a centimeter. Recall that protostome and deuterostomes differ in certain aspects of their embryonic development, and they are named based on which opening of the digestive cavity develops first. One of the candidate hypotheses is presented below. Animal phyla are further divided into classes, orders, families, genera, and species. We also use third-party cookies that help us analyze and understand how you use this website. Cnidaria are neither protostomes or deuterostome, as both of these superphylum belong to the Bilateria clade of animals, animals that exhibit. In more primitive organisms the coelom can serve as // -->