In Biology, What is Subregenum Bilateria?
Bilateria is a subregenum, or subkingdom of the Animal Kingdom in general. It consists of all animals except for sponges, cnidarians (jellyfish and relatives), and ctenophore (comb jellies). Bilaterians share many common characteristics, including three primary tissue layers (also called germ layers), bilateral symmetry, a coelom (body cavity), and usually, sophisticated organs and body morphology. All complex animals are part of Bilateria, as two germ layers (possessed by non-bilaterians) is not enough to sculpt sophisticated morphologies. The first known bilaterian lived about 600 million years ago in China. Just between 0.1 and 0.2 mm (100 and 200 microns) in diameter, this tiny spherical animal was named Vernanimacula, which means “little spring animal.” The animal was given this name because it evolved shortly after the Marinonan Glaciation, the most severe Ice Age in the history of the planet, which lasted about 50 million years. Something closely related to Vernanimacula is prob
