Symmetry in biology Most radially symmetric animals are symmetrical about an axis extending from the center of the oral surface, which contains the mouth to the center of the opposite, , end. Radial symmetry is especially suitable for sessile animals such as the sea anemone, floating animals such as jellyfish, and slow moving organisms such as starfish. Animals in the phyla Cnidaria and Echinodermata are radially symmetric, although many sea anemones and some corals have bilateral symmetry defined by a single structure, the siphonoglyph. Many flowers are radially symmetric or actinomorphic. Roughly identical flower parts – petals, sepals, and stamens – occur at
Domestication The phyla involved are Cnidaria, Platyhelminthes (for biological control), Annelida, Mollusca, Arthropoda (marine crustaceans as well as insects and spiders), and Echinodermata. While many marine molluscs are used for food, only a few have been domesticated, including squid, cuttlefish and octopus, all used in research on behaviour and neurology. Terrestrial snails in the genera "Helix" and "Murex" are raised for food. Several parasitic or parasitoidal insects including the fly "Eucelatoria", the beetle "Chrysolina", and the wasp "Aphytis" are raised for biological control. Conscious or unconscious artificial selection has many effects on species under domestication; variability can readily be lost by