Radial symmetry is usually associated with

Options

A. aquatic mode of life
B. lower grade of organisation
C. creeping mode of locomotion
D. sedentary mode of life

Explanation

### Step-by-Step Text Solution:

1. **Understanding Symmetry in Animals**:
- Symmetry refers to the balanced proportions of an organism. Animals can be categorized based on their symmetry into three types: asymmetrical, radially symmetrical, and bilaterally symmetrical.

2. **Defining Radial Symmetry**:
- Radial symmetry is a form of symmetry where an organism can be divided into similar halves by multiple planes passing through a central axis. An example of this is an apple or a jellyfish, where you can cut through the center in various directions and still get equal halves.

3. **Identifying Organisms with Radial Symmetry**:
- Organisms that exhibit radial symmetry are typically found in lower grades of organization. This includes members of the phylum Cnidaria, such as sea jellies (jellyfish) and sea anemones, which are examples of radially symmetrical organisms.

4. **Comparing with Other Symmetries**:
- In contrast, bilateral symmetry allows an organism to be divided into two equal halves by only one plane, such as humans and many other animals. This type of symmetry is associated with higher levels of organization, such as organ and organ system levels.

5. **Conclusion**:
- Therefore, radial symmetry is usually associated with simpler, lower-grade organisms, particularly those found in aquatic environments, such as members of the phylum Cnidaria.

### Final Answer:
Radial symmetry is usually associated with organisms like jellyfish and sea anemones, which belong to the phylum Cnidaria.

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