Platyhelminthes are characterised by

Options

A. Lack of organistaion
B. presence of flame cells
C. diploblastic nature
D. bioluminescence

Answer

To answer the question "Platyhelminthes are characterised by," we will analyze the provided options and determine which one correctly describes the characteristics of the phylum Platyhelminthes.

### Step-by-Step Solution:

1. **Understanding Platyhelminthes**:
- Platyhelminthes, commonly known as flatworms, are a phylum of invertebrate animals. They are characterized by their flat, ribbon-like bodies that are dorsoventrally flattened.

2. **Analyzing the Options**:
- **Option A: Lack of organization**: This option suggests that Platyhelminthes have no organization. However, this is incorrect as they exhibit an organ level of organization.
- **Option B: Presence of flame cells**: Flame cells are specialized excretory cells found in Platyhelminthes that play a crucial role in osmoregulation and excretion. This option is a strong candidate.
- **Option C: Diploplastic nature**: This option states that Platyhelminthes are diploblastic. This is incorrect because Platyhelminthes are triploblastic, meaning they have three germ layers: ectoderm, mesoderm, and endoderm.
- **Option D: Bioluminescence**: This option claims that Platyhelminthes exhibit bioluminescence. This is incorrect as bioluminescence is a characteristic of other phyla, such as Cnidaria (e.g., jellyfish).

3. **Conclusion**:
- After analyzing all the options, the correct answer is **Option B: Presence of flame cells**. Flame cells are indeed a characteristic feature of Platyhelminthes.

### Final Answer:
Platyhelminthes are characterised by the **presence of flame cells**.

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