Anterior refers to the head end of a bilaterally symmetrical animal. The word posterior refers to the rear end or tail end.
Assuming you mean two symmetrical sides, the term is called bilaterally symmetric.
Echinoderms are thought to have evolved from bilaterally symmetrical ancestors because their larval forms exhibit bilateral symmetry. Over time, echinoderms undergo a process called pentaradial symmetry, where they develop a five-point radial symmetry characteristic of adult echinoderms. This suggests a modification from bilateral to radial symmetry during evolution.
cnidarians
true
The front portion of the body is called the anterior aspect or the ventral side.
Animals of the phylum Platyhelminthes are known as flatworms because their bodies are dorsoventrally flattened, giving them a thin and flat appearance. This flat body shape allows for efficient gas exchange and nutrient absorption through their body surface.
Platyhelminthes are bilaterally symmetrical, nonsegmented, dorsoventrally flattened worms characterized by lack of coelom, anus, circulatory and respiratory systems, and exo- or endoskeleton. Nematoda are bilaterally symmetrical and usually tapered at both ends. Some species have separate sexes; others are hermaphroditic.Nematodes have a unique excretory system consisting, in simpler species, of one or two one-celled glands called renette cells and, in more highly specialized forms, of longitudinal excretory ducts. Earthworm (phylum annelid)- The body is annular, made up of segments that are most specialized in the rear. Earthworms have a simple circulatory system. They have two main blood vessels that extend through the length of their body: a ventral blood vessel which leads the blood to the posterior end, and a dorsal blood vessel which leads to the anterior end. Unlike platyhelminthes and nematoda, they do possess a body cavity (coelom).
Platyhelminthes are bilaterally symmetrical, nonsegmented, dorsoventrally flattened worms characterized by lack of coelom, anus, circulatory and respiratory systems, and exo- or endoskeleton. Nematoda are bilaterally symmetrical and usually tapered at both ends. Some species have separate sexes; others are hermaphroditic. Nematodes have a unique excretory system consisting, in simpler species, of one or two one-celled glands called renette cells and, in more highly specialized forms, of longitudinal excretory ducts. Earthworm (phylum annelid)- The body is annular, made up of segments that are most specialized in the rear. Earthworms have a simple circulatory system. They have two main blood vessels that extend through the length of their body: a ventral blood vessel which leads the blood to the posterior end, and a dorsal blood vessel which leads to the anterior end. Unlike platyhelminthes and nematoda, they do possess a body cavity (coelom).
The anterior end of the sperm is called the head. It contains the genetic material (DNA) necessary for fertilization.
Poplitil
incisal
Symmetrical