Table of Contents
Why is bilateral symmetry important in the evolution?
Having bilaterally symmetrical bodies (the same on both sides along an axis) permit them to propel forward in a straight line. In evolutionary history, animals that moved quickly and efficiently from point A to point B would have been more successful and selected for than those who were ineffective at locomoting.
What era did bilateral symmetry evolve?
It is likely that the ancestor of Bilateria appeared at the end of the Vendian period which is the last geological period of the Neoproterozoic Era preceding the Cambrian Period. It lasted from approximately 635 to 541±1 million years ago.
What did the evolution of a bilateral body plan allow to develop?
The evolution of bilateral symmetry that allowed for the formation of anterior and posterior (head and tail) ends promoted a phenomenon called cephalization, which refers to the collection of an organized nervous system at the animal’s anterior end.
What is the evolutionary significance of symmetry?
The symmetry of an animal generally fits its lifestyle. For example, many radial animals are sessile forms or plankton and their symmetry equips them to meet their environment equally well from all sides. More active animals are generally bilateral.
Why was bilateral symmetry such a turning point in evolution of animals?
Bilateral symmetry is an important development in the evolution of animals. In invertebrates with bilateral symmetry, sense organs and nerves tend to be concentrated in front of their body. Such invertebrates can respond better to the environmental stimulus.
Where did bilateral symmetry come from?
Bilateral symmetry with two body axes arose early in animal evolution, probably in slow, flat, worm-like organisms locomoting on a substrate [2].
Do humans have bilateral symmetry?
The body plans of most animals, including humans, exhibit mirror symmetry, also called bilateral symmetry. They are symmetric about a plane running from head to tail (or toe). Therefore, bilateral symmetry must have evolved for a reason, the thinking goes.
What are the disadvantages of bilateral symmetry?
The biggest disadvantage of bilateral symmetry is the fact that there is so little diversity in the structure , which makes it a big problem as far as evolution and adaptability is concerned.
What are facts about bilateral symmetry?
There are three basic forms: Radial symmetry: The organism looks like a pie. This pie can be cut up into roughly identical pieces. Bilateral symmetry: There is an axis; on both sides of the axis the organism looks roughly the same. Spherical symmetry: If the organism is cut through its center, the resulting parts look the same.
What is an example of an animal with bilateral symmetry?
Most creatures we see around us have bilateral symmetry. Examples are worms, insects, spiders, fish, birds and mammals, including humans. In evolution, bilateral symmetry was an important step toward the development of a head and the concentration of sensory organs.
What are the advantages of bilateral symmetry in animals?
Advantages of Symmetry: Bilateral symmetry is associated with the term cephalization-meaning the specialization of the anterior end of the body to form the head where the nervous tissues, sense organs and feeding Other advantages of this symmetry are the streamlining of the body, development of different organs in different body regions and more efficient unidirectional movement. ADVERTISEMENTS: Radial symmetry helps the animals for collecting food and defence.