Coelenterates, also known as Cnidarians, are a group of simple aquatic animals that include jellyfish, sea anemones, and corals. In contrast to other metazoans, which are multicellular animals, coelenterates exhibit radial symmetry.

Radial Symmetry:
- Coelenterates exhibit radial symmetry, meaning they have body parts arranged around a central axis. This allows them to be symmetrical in any plane passing through the central axis.
- This symmetry is advantageous for coelenterates as it allows them to sense and respond to stimuli from all directions.
- It also helps them in capturing prey and defending themselves.

Advantages of Radial Symmetry in Coelenterates:
1. Sensory Abilities:
- With radial symmetry, coelenterates have sensory organs, such as tentacles or specialized cells, distributed evenly around their bodies.
- This allows them to detect and respond to various stimuli, including light, touch, and chemicals, from any direction.
- They can efficiently orient themselves towards food sources or move away from potential threats.

2. Efficient Capture of Prey:
- Coelenterates possess specialized stinging cells called nematocysts.
- These nematocysts are located on their tentacles and are used to capture prey.
- With radial symmetry, coelenterates can extend their tentacles in all directions, increasing their chances of capturing prey.

3. Enhanced Defense Mechanisms:
- Coelenterates can use their nematocysts not only for capturing prey but also for defense against predators.
- Radial symmetry allows them to effectively respond to threats from any direction.
- When threatened, they can quickly discharge their nematocysts, releasing venomous threads that can immobilize or deter predators.

4. Reproduction and Polymorphism:
- Coelenterates exhibit various modes of reproduction, including sexual and asexual.
- Radial symmetry allows them to produce gametes or gemmules (asexual reproductive structures) at multiple sites on their body, increasing their reproductive efficiency.
- Some coelenterates also exhibit polymorphism, where different individuals within a species have different body forms and functions. Radial symmetry facilitates the development of these specialized structures in different regions of the body.

In conclusion, coelenterates exhibit radial symmetry, which provides them with advantages in terms of sensory abilities, efficient prey capture, enhanced defense mechanisms, and reproductive strategies. This distinguishes them from other metazoans, which display different types of symmetry.