Dentist specialties are recognized in those areas where advanced knowledge and skills are essential to maintain or restore oral health. The list of recognized dental specialties differs from country to country.
In contrast, radially symmetrical animals like jellyfish have a topside and a downside, but no identifiable front or back. The bilateria are a major group of animals, including the majority of phyla but not sponges, cnidarians, placozoans and ctenophores. For the most part, bilateral embryos are triploblastic, having three germ layers: endoderm, mesoderm, and ectoderm.
bilateral symmetry the configuration of an irregularly shaped body (such as the human body or that of higher animals) that can be divided by a longitudinal plane into halves that are mirror images of each other. radial symmetry that in which the body parts are arranged regularly around a central axis.adial symmetry that in which the body parts are arranged regularly around a central axis.