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Biradial symmetry is found in organisms which show morphological features (internal or external) of both bilateral and radial symmetry. Unlike radially symmetrical organisms which can be divided equally along many planes, biradial organisms can only be cut equally along two planes.
Fish: Dorsal view of right-bending (left) and left-bending (right) jaw morphs [4]. Many flatfish, such as flounders, have eyes placed asymmetrically in the adult fish.The fish has the usual symmetrical body structure when it is young, but as it matures and moves to living close to the sea bed, the fish lies on its side, and the head twists so that both eyes are on the top.
The organism's body is bilaterally symmetrical, however, its anterior displays external radial symmetry. Like some other modern invertebrates, a cuticle restricts the size of and protects the animal.
This ancestral organism adopted an attached mode of life with suspension feeding, and developed radial symmetry. Even so, the larvae of all echinoderms are bilaterally symmetrical, and all develop radial symmetry at metamorphosis. Like their ancestor, the starfish and crinoids still attach themselves to the seabed while changing to their adult ...
Cnidarians are defined by their two distinct tissue layers and radial symmetry. These characteristics distinguish them from invertebrates of the clade bilateria, which possess bilateral symmetry in their adult or larval forms. Hydrozoans can be colonial or solitary organisms and are often very small on their own.
Of all echinoderms, the Ophiuroidea may have the strongest tendency toward five-segment radial (pentaradial) symmetry. The body outline is similar to that of starfish, in that ophiuroids have five arms joined to a central body disk. However, in ophiuroids, the central body disk is sharply marked off from the arms. [5]
The bodies of adult sand dollars, like those of other echinoids, display radial symmetry. The petal-like pattern in sand dollars consists of five paired rows of pores. The pores are perforations in the endoskeleton through which podia for gas exchange project from the body. The mouth of the sand dollar is located on the bottom of its body at ...
Rugose corals will sometimes have dissepiments, which are curved plates connected to septa and tabulae. The symmetry can be distinguished by the orientation of septa in a transverse section of the coral. Rugose corals always display bilateral symmetry whereas tabulate and scleractinian corals show radial symmetry.