Medicine

Difference Between Radial Symmetry and Bilateral Symmetry

Main difference

The main difference between radial symmetry and bilateral symmetry is that radial symmetry produces mirror images around the central axis and bilateral symmetry produces left and right sides.

Radial Symmetry vs. Bilateral Symmetry

Radial symmetry produces identical halves of the body along the central axis, while bilateral symmetry produces the left and right sides along the sagittal plane. Radial symmetry arranges the body parts in a regular pattern along the central axis, while bilateral symmetry arranges the body parts equally on both the left and right sides. Radial symmetry is good for the sessile organism while bilateral symmetry allows for good movements. Radial symmetry does not allow quick access to food. On the other hand, bilateral symmetry allows quick access to food. Radial symmetry does not lead to head development in the front of the body, while bilateral symmetry leads to head development in the front of the body.

Comparison chart

radial symmetry two-sided symmetry
Radial symmetry is the arrangement of organism parts such that when the organism passes through the center of the structure from any direction, it produces two halves that are mirror images of each other. Bilateral symmetry is the arrangement of body parts into left and right halves such that they are mirror images along the central axis.
body division
Do not divide the body into left and right sides Divide the body into left and right by sagittal plane
head development
Head development at the front of the body is rare. The development of the head at the front of the body is an important feature.

examples

jellyfish
Sea urchin
Sea anemone
Humans
insects
Crustaceans

What is radial symmetry?

Radial symmetry is defined as the arrangement of parts in organisms in such a way that when a cut is made through the center of the structure from any direction, two halves are produced that are mirror images of each other. For example, in plants, stems and roots exhibit radial symmetry, and in animals, radial symmetry is shown by organisms in the phylum Cnidaria and Echinodermata. Flowers also exhibit radial symmetry, but in flowers, radial symmetry is called actinomorphy. All organisms that exhibit radial symmetry resemble a cake and produce identical pieces when cut from any plane. Radially symmetric animals are mostly symmetric about their axis. Radial symmetry is good for sessile organisms, slow-moving organisms, and floating organisms, for example, sea anemone, starfish, and jellyfish, respectively. Radial symmetry has some special forms like tetrameric, pentamers, hexamers, and octamers. The radial symmetry of tetramerism is exhibited by the jellyfish, as it has four channels arranged radially. Pentamerism is also called pentaradial or pentagonal symmetry. Pentamerism describes the organism as having five parts around a central axis, which are 72° apart. Examples of pentamerism are members of echinoderms such as a sea urchin. The hexamer is found in organisms that have a hexameric body plan, their polyps have tentacles in a multiple of six, and possess six times greater internal symmetry. Examples of hexameric display organisms are corals and sea anemones. The octamer is found in corals that have polyps with eight tentacles and that possess octameric radial symmetry. The radial symmetry of tetramerism is exhibited by the jellyfish, as it has four channels arranged radially. Pentamerism is also called pentaradial or pentagonal symmetry. Pentamerism describes the organism as having five parts around a central axis, which are 72° apart. Examples of pentamerism are members of echinoderms such as a sea urchin. The hexamer is found in organisms that have a hexameric body plan, their polyps have tentacles in a multiple of six, and possess six times greater internal symmetry. Examples of hexameric display organisms are corals and sea anemones. The octamer is found in corals that have polyps with eight tentacles and that possess octameric radial symmetry. The radial symmetry of tetramerism is exhibited by the jellyfish, as it has four channels arranged radially. Pentamerism is also called pentaradial or pentagonal symmetry. Pentamerism describes the organism as having five parts around a central axis, which are 72° apart. Examples of pentamerism are members of echinoderms such as a sea urchin. The hexamer is found in organisms that have a hexameric body plan, their polyps have tentacles in a multiple of six, and possess six times greater internal symmetry. Examples of hexameric display organisms are corals and sea anemones. The octamer is found in corals that have polyps with eight tentacles and that possess octameric radial symmetry. they are 72° apart. Examples of pentamerism are members of echinoderms such as a sea urchin. The hexamer is found in organisms that have a hexameric body plan, their polyps have tentacles by a multiple of six, and possess six times greater internal symmetry. Examples of hexameric display organisms are corals and sea anemones. The octamer is found in corals that have polyps with eight tentacles and that possess octameric radial symmetry. they are 72° apart. Examples of pentamerism are members of echinoderms such as a sea urchin. The hexamer is found in organisms that have a hexameric body plan, their polyps have tentacles in a multiple of six and possess six times greater internal symmetry. Examples of hexameric display organisms are corals and sea anemones. The octamer is found in corals that have polyps with eight tentacles and that possess octameric radial symmetry.

What is Bilateral Symmetry?

Bilateral symmetry is defined as the arrangement of body parts into left and right halves such that they are mirror images along the central axis. Bilateral is a combination of two words, i.e. bi, which means two, and latus, which means side. Similarly, the word symmetry is also a combination of two words, i.e. syn meaning together and metron meaning meter. Bilateral symmetry is also called left/right symmetry. The left and right halves are not the same, but the fact is that many organisms exhibit bilateral symmetry, approximately 90% including the most advanced human creatures. All vertebrates and a small number of invertebrates show bilateral symmetry. The plane that divides the body vertically into left and right halves is called the sagittal plane. Bilateral symmetry is therefore reflection symmetry. Animals that possess bilateral symmetry exhibit a type of movement that refers to one end of the body as the leading end. Organisms that have bilateral symmetry should have head and tail, anterior and posterior, superior and inferior, and left and right regions. Bilateral symmetry allows organisms to move faster compared to any other body symmetry. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy. Bilateral symmetry allows organisms to move faster compared to any other body symmetry. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy. Bilateral symmetry allows organisms to move faster compared to any other body symmetry. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy. Bilateral symmetry allows organisms to move faster compared to any other body symmetry. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy. Bilateral symmetry allows organisms to move faster compared to any other body symmetry. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy. Bilateral symmetry also allows organisms to easily find food or avoid predators. Flowers also possess bilateral symmetry, and in flowers, bilateral symmetry is called zygomorphy.

Key differences

  1. Radial symmetry produces identical halves of the body along the central axis, while bilateral symmetry produces the left and right sides along the sagittal plane.
  2. Radial symmetry does not produce the right and left halves of the body, on the other hand, bilateral symmetry produces the right and left halves of the body.
  3. Radial symmetry produces mirror images, while bilateral symmetry does not produce mirror images.
  4. Radial symmetry arranges the body parts in a regular pattern along the central axis, while bilateral symmetry arranges the body parts equally on both the left and right sides.
  5. Radial symmetry does not lead to head development in the front of the body, while bilateral symmetry leads to head development in the front of the body.

Final Thought

The conclusion from the above discussion is that radial and bilateral symmetry is the arrangement of the body parts of the organism and differentiates the organisms into two classes based on the arrangement of the body parts in the organisms.

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