Which of these statements is incorrect about Platyhelminthes ?

Options

A. Some members like Planaria possess high regeneration capacity .
B. They are bilaterally symmetrical , triploblastic and acoelomate animals with organ level of organisation.
C. Their sexes are separate , fertilisation is internal and development is through many larval stages.
D. They have specialized cells called flame cells which help in osmoregulation and excretion.

Answer

To determine which statement is incorrect about Platyhelminthes, we will analyze each statement provided in the options.

### Step-by-Step Solution:

1. **Understanding Platyhelminthes**:
- Platyhelminthes, commonly known as flatworms, are a group of invertebrates that exhibit certain key characteristics.

2. **Analyzing the Statements**:
- **Statement 1**: "Some members like planaria possess high regeneration capacity."
- This statement is **correct**. Planaria are known for their remarkable ability to regenerate lost body parts.

- **Statement 2**: "They are bilaterally symmetrical triploblastic acoelomate animals with organ level of organization."
- This statement is also **correct**. Platyhelminthes exhibit bilateral symmetry, are triploblastic (having three germ layers), and are acoelomate (lacking a true coelom). They have an organ level of organization.

- **Statement 3**: "Their sexes are separate. Fertilization is internal and development is through many larval stages."
- This statement is **incorrect**. Platyhelminthes are primarily hermaphrodites, meaning that they possess both male and female reproductive organs within the same individual. While some may have separate sexes, it is not the general rule for the entire group.

- **Statement 4**: "They have specialized cells called flame cells which help in osmoregulation and excretion."
- This statement is **correct**. Flame cells are indeed specialized excretory cells in Platyhelminthes that play a role in osmoregulation and excretion.

3. **Conclusion**:
- The incorrect statement about Platyhelminthes is **Statement 3**: "Their sexes are separate. Fertilization is internal and development is through many larval stages."

### Final Answer:
The incorrect statement about Platyhelminthes is that their sexes are separate; they are primarily hermaphroditic.

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