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Symmetry in biology is about the overall shape of the body and its parts. The body plans of most multicellular organisms have some form of symmetry, radial symmetry, bilateral symmetry or spherical symmetry.
- Bilateral Symmetry Definition
- Examples of Bilateral Symmetry
- Related Biology Terms
- Quiz
Bilateral symmetry refers to organisms with body shapes that are mirror images along a midline called the sagittal plane. The internal organs, however, are not necessarily distributed symmetrically. The vast majority of animals display bilateral symmetry; also known as plane symmetry, this is a trait that applies to 99% of all animals, in the major...
Butterflies
Butterflies are an excellent example of near perfect bilateral symmetry. Not only do they have a body shape that can be divided into symmetrical halves, but also the patterns on each wing of a butterfly are near identical to each other.
Humans
The bilateral symmetry in humans has been widely studied, and many advantages of the body type have been determined. It may help us to help the brain recognize when different part of the body are in different positions, making visual perception easier and better coordination of movement. Symmetry is also beneficial in terms of balance, and is important for forward-propelling movement in a specific direction as well as making the process of movement easier; for example, if a human had one leg...
Bivalve Mollusks
Bivalve mollusks are a class of marine or freshwater organisms that have shells consisting of two hinged, bilaterally symmetrical halves; however, some species have secondarily lost their bilateral symmetry, for example oysters and gastropods such as snails. In this group of organisms, the sagittal plane lies along the hinge, which allows the organism to firmly close its shell and protect the soft inner body. The image shows the shell and internal body of a bivalve mussel. The symmetry of the...
Radial Symmetry– Refers to an organism, which has several planes that it could be cut through, to produce roughly identical pieces.Spherical Symmetry– Refers to organisms, which could be cut directly through the center in any direction without distinguishable difference between segments.Body Plan– The group of morphological characteristics, which can identify an organism as belonging to a particular taxonomic group, such as a phylum.1. Which area of the body does cephalization occur? A. The Ventral Side (the bottom) B. The Dorsal Side (the top) C. The Anterior Side (the head) D.The Posterior Side (the tail end) 2. Which of the following is ¬not an advantage of bilateral symmetry? A. Better control of movement direction B. Indication of poor health C. Better Visual perception D...
symmetry, in biology, the repetition of the parts in an animal or plant in an orderly fashion. Specifically, symmetry refers to a correspondence of body parts, in size, shape, and relative position, on opposite sides of a dividing line or distributed around a central point or axis.
- The Editors of Encyclopaedia Britannica
Oct 22, 2021 · Examples of animals with radial symmetry are jellyfish, sea urchins, and sea stars. The bodies of most animals can be divided into equal left and right halves along the central axis and this is known as bilateral or mirror symmetry.
Nov 13, 2020 · Bilateral symmetry in flowers evolved in relation to attracting specific pollinators and developed from earlier radially symmetrical forms (for more see Symmetry in Organismal Biology). These gazanias (probably hybrids, which I photographed in the Western Cape), are a spectacular example of flowers with radial symmetry.
The type of symmetry is found in some sponges (Sycon), cnidarians (e.g. Hydra jelly), and echinoderms (e.g. star fish). When the body can be divided into two similar halves by one or two vertical planes only, the radial symmetry is called biradial symmetry.
