Which of the following statements is incorrect with regard to bilateral symmetry ?

Options

A. Body can be divided into two equal halves by a single plane only
B. The organisms that show bilateral symmetry have paired body organs that occur on the two sides of central axis
C. It is found in all invertebrates and few vertebrates
D. Spider and crab show bilateral symmetry

Answer

To determine which statement is incorrect regarding bilateral symmetry, we can follow these steps:

### Step-by-Step Solution:

1. **Define Bilateral Symmetry**:
- Bilateral symmetry refers to a body plan in which the left and right sides of an organism are mirror images of each other. This means that the organism can be divided into two equal halves along a single plane.

2. **Identify Organisms with Bilateral Symmetry**:
- Bilateral symmetry is commonly found in most vertebrates (like mammals, birds, reptiles, etc.) and some invertebrates (like certain mollusks and arthropods).

3. **Characteristics of Bilateral Symmetry**:
- Organisms exhibiting bilateral symmetry typically have paired body organs. These paired organs are arranged on either side of a central axis, allowing for symmetry.

4. **Examples of Bilateral Symmetry**:
- Common examples include spiders and crabs, which are both arthropods that demonstrate bilateral symmetry.

5. **Evaluate the Statements**:
- Given the statements, we need to identify which one incorrectly describes bilateral symmetry.
- The incorrect statement would likely misrepresent the prevalence of bilateral symmetry in vertebrates and invertebrates.

6. **Conclusion**:
- After analyzing the statements, we find that the statement claiming bilateral symmetry is "mostly found in invertebrates" is incorrect. Bilateral symmetry is predominantly found in vertebrates.

### Final Answer:
The incorrect statement regarding bilateral symmetry is that it is "mostly found in invertebrates."

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