1. Bilateral symmetry: Most animals, including humans, exhibit bilateral symmetry, which means that their bodies can be divided into two mirror-image halves along a central axis. This type of symmetry allows for greater specialization and complexity of body parts, as each side of the body can perform different functions.
1. Radial symmetry: Animals with radial symmetry, such as jellyfish and sea urchins, have a body plan that can be divided into multiple identical parts around a central axis. While radial symmetry may appear simpler than bilateral symmetry, it also imposes limitations on complexity, as there is less scope for specialization.
2. Complexity of body systems: Bilaterally symmetrical animals generally have more complex body systems and adaptations compared to radial symmetrical animals. The presence of bilateral symmetry allows for the development of specialized structures like appendages, sense organs, and digestive systems, all of which contribute to increased complexity.
3. Evolutionary relationships: Symmetry is considered an important characteristic in understanding the evolutionary relationships between different animal groups. The presence or absence of bilateral symmetry, and the degree of complexity within symmetrical body plans, are factors that help classify and distinguish between different taxa.
The relationship between symmetry and complexity is not absolute, as there are exceptions and variations across different animal groups. However, in general, bilaterally symmetrical animals exhibit greater complexity in terms of body organization, function, and adaptations compared to radially symmetrical animals.