Symmetry in biology
Introduction
Symmetry in biology is the balanced distribution of duplicate body parts or shapes within the body of an organism. In biology, symmetry is widely observable in organisms, including animals and plants. The term symmetry in biology is derived from the Greek word symmetria, meaning 'agreement in dimensions, due proportion, arrangement'.
Types of Symmetry in Biology
There are several types of symmetry in biology, including radial, bilateral, and spherical symmetry.
Radial Symmetry
Radial symmetry is a type of symmetry where an organism can be divided into similar halves by more than two planes passing through the center. This type of symmetry is primarily characteristic of sessile or free-floating organisms, such as sea anemones, jellyfish, and many microscopic organisms.
Bilateral Symmetry
Bilateral symmetry is a type of symmetry in which an organism can be divided into identical halves by a single plane. This type of symmetry is common in higher organisms, such as humans and other mammals, birds, reptiles, and fish.
Spherical Symmetry
Spherical symmetry is a type of symmetry in which any plane passing through the center divides the organism into mirrored halves. This type of symmetry is rare and is primarily found in some protozoa and other microscopic organisms.
Evolution of Symmetry in Biology
The evolution of symmetry in biology is a complex process that is influenced by a variety of factors, including genetic and environmental influences.
Genetic Influences
The genetic basis of symmetry in biology is a topic of ongoing research. However, it is known that certain genes, known as Hox genes, play a crucial role in determining the body plan of an organism, including its symmetry.
Environmental Influences
Environmental factors can also influence the symmetry of an organism. For example, the direction and intensity of light can influence the symmetry of plant leaves and flowers.
Symmetry and Function
The symmetry of an organism often correlates with its function or behavior. For example, organisms with bilateral symmetry often exhibit directional movement, while organisms with radial or spherical symmetry are typically sessile or exhibit non-directional movement.
Symmetry and Development
Symmetry in biology also plays a crucial role in the development of an organism. During embryonic development, the body plan of the organism, including its symmetry, is established.
Symmetry and Disease
Symmetry in biology can also be used as an indicator of disease. For example, asymmetry in human faces can be a sign of certain genetic disorders.