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.
radial symmetry - the property of symmetry about an axis; the starfish illustrates radial symmetry math, mathematics, maths - a science (or group of related sciences) dealing with the logic of quantity and shape and arrangement