what is the difference between radial symmetry and bilateral symmetry since in both the body has to be divided into two equal halves.
Bilateral symmetry:-Bilateral symmetry is the symmetrical arrangement of an organism or a body part along a central axis. As a result of which the body is divided into equivalent. It can be observed in organisms of phylum Platy helminthes. Radial symmetry is a type of symmetry in which the body of the organism into two equal halves by any plane passing through the central axis. Radial symmetry can be observed in the animals of the phylum Echinoderm
Sea anemones display radial symmetry.These organisms resemble a pie where several cutting planes produce roughly identical pieces. An organism with radial symmetry exhibits no left or right sides. They have a top and a bottom (dorsal and ventral surface) only.
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, or aboral, end. This type of symmetry is especially suitable for sessile animals such as the sea anemone , floating animals such as jellyfish, and slow moving organisms such as starfish.
In bilateral symmetry (also called plane symmetry), only one plane, called the sagittal plane, will divide an organism into roughly mirror image halves. Thus there is approximate reflection symmetry. Often the two halves can meaningfully be referred to as the right and left halves, e.g. in the case of an animal with a main direction of motion in the plane of symmetry
If the body of an animal is divided into two equal parts by cutting it in any plane passing through the centre of its body, then the body of the animal is said to have radial symmetry.
If the body of an animal is divided into left and right halves by one plane only, then the body of the animal is said to have bilateral symmetry.
Animals of phylum coelenterate are radially symmetrical.
Animals of phylum helminthes and higher phyla are bilaterally symmetrical.
In bilateral symmetry (also called plane symmetry), only one plane, called the sagittal plane , will divide an organism into roughly mirror image halves (with respect to external appearance only, seesitus solitus ). Thus there is approximate reflection symmetry . Often the two halves can meaningfully be referred to as the right and left halves, e.g. in the case of an animal with a main direction of motion in the plane of symmetry.
In radial symmetry, any plane passing through the body into two identically equal parts whereas in bilateral symmetry a plane passing through the central axis divides the organism's body into the right and left part. Examples of radial and bilateral symmetry are Starfish, Octopus and Man, Butterfly respectively.
Radial symmetry is essentially circular- with one center point, the shape or design of the organism will be symmetrical around that point.
Bilateral symmetry is like drawing a line through the center of the organism, and having two matching sides. A butterfly is a great example of this, or a sea star.
An animal's body has bilateral symmetry when its right and left halves of the body have the same body design
Radial Symmetry:A type of symmetry having only one body axis , through which the body can be divided into multiple planes to give mirror- image. Eg: starfish,jellyfish,sea urchins,corals.
BILATERAL SYMMETRY: those animals which can be divided in two equal parts when cut through only a single plain then those animals are said to have bilateral symmetry. EG: cnidaria
What is the difference between Radial and Bilateral Symmetry?
• Bilateral symmetry has a symmetric plane while radial symmetry has a symmetric axis.
• Only two similar portions can be identified from bilateral symmetry whereas, from radial symmetry few similar portions of the body can be identified.
• All the radially symmetric animals are found in water, but bilaterally symmetric animals are found in both aquatic and terrestrial habitats.
• Bilateral symmetry is more common than radial symmetry among animals. In fact, there are more animal phyla with bilateral symmetry compared to radial symmetry.
Ex :coelenterates. This in case of radial symmetry
Where as in bilateral symmetry the body can be divided into idenileft and right halves in only one plane
Ex : Annelids and molluscus