Dictionary » S » Symmetry



noun, plural: symmetries

Correspondence of parts (in terms of form, size, distribution, or arrangement) on opposite sides of a dividing plane or on sides around an axis


In biology, symmetry pertains to an attribute of organisms showing regularity in parts on a plane or around an axis. Symmetry may be:

  • bilateral symmetry – symmetry in which the opposite sides are similar; the external appearance is the same on the left and right sides in a sagittal plane (such as the body plan of most animals, including humans)
  • radial symmetry – symmetry in which the sides exhibit correspondence or regularity of parts around a central axis; lacking left and right sides (e.g. sea stars, sea anemones, jellyfish, sea urchins, and many flowers)

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Locomotory Evolution

There are advantages to both types of body symmetry. a bilaterian fish enjoys much faster, unidirectional movement compared to a jellyfish. This could be advantages if the bilaterian is a predator or a prey for example. in the cambrain explosion ...

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by Youngji
Sun Feb 01, 2015 12:36 pm
Forum: Evolution
Topic: Locomotory Evolution
Replies: 1
Views: 1486

Book recommendation for exam

... Acoelomata and Coelomata; Protostomes and Deuterostomes, Bilateralia and Radiata; Status of Protista, Parazoa, Onychophora and Hemichordata; Symmetry. 3. Protozoa : Locomotion, nutrition, reproduction; evolution of sex; General features and life history of Paramaecium, Monocystis, Plasmodium, ...

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by bertstare
Sun Oct 21, 2012 2:19 pm
Forum: Zoology Discussion
Topic: Book recommendation for exam
Replies: 3
Views: 8481


... The biological DNA is only a new shape of this universal matrix, with increased level of complexity. The formula is composed by bi-lateral symmetry in all aspects, so, in its energy also. There is the growing energy and the decaying energy, which could be oja e teja, or yin and yang. So, ...

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by TheMatrixDNA
Sun Jul 29, 2012 9:29 pm
Forum: General Discussion
Topic: The question of life...
Replies: 47
Views: 39376

Please check my work?

... so don't laugh at me k thanks :* Which of the following are three common characteristics of echinoderms? A tube feet, circulatory system, body symmetry B marine-dwellers, endoskeletons, water-vascular system C bilateral symmetry, ossicles, respiratory system D mouths, protosomes, body symmetry ...

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by radicali
Thu Jun 14, 2012 8:57 pm
Forum: General Discussion
Topic: Please check my work?
Replies: 1
Views: 3571

Evolution of the Face and Head

The generally-accepted connection is not with feeding, but with symmetry and movement - bilateral animals, with propulsion driven equally from 2 sides, wind up with a directionality and a front end. Packing sense receptors and processors there, to deal with ...

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by Darby
Thu May 10, 2012 2:15 pm
Forum: Evolution
Topic: Evolution of the Face and Head
Replies: 5
Views: 5217
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