Which of the following is not a characteristic feature of phylum echinodermata?

Options

A. Excretory system is absent
B. Presence of water vascular system which helps in locomotion
C. Sexes are separate
D. Festilisation is internal development is indirect with free swimming larva

Explanation

To determine which of the following is not a characteristic feature of the phylum Echinodermata, we can analyze each option provided in the question step by step:

### Step 1: Identify the Characteristics of Echinodermata
Echinodermata is a phylum that includes marine animals such as starfish, sea urchins, and sea cucumbers. Some key characteristics of this phylum include:
- Presence of a water vascular system.
- Radial symmetry in adults.
- A calcareous endoskeleton.
- External fertilization with indirect development (free-swimming larvae).
- Lack of a well-developed excretory system.

### Step 2: Analyze Each Statement
1. **Excretory system is absent**: This is true for Echinodermata. They do not have a specialized excretory system; instead, waste is expelled through the surface of their body.

2. **Presence of a vascular system helps in locomotion**: This is also true. Echinoderms have a water vascular system that aids in locomotion and feeding.

3. **The sexes are separate**: This statement is true as well. Echinoderms are generally unisexual, meaning individuals are either male or female.

4. **Fertilization is internal; development is indirect with free-swimming larvae**: This statement is incorrect. Echinoderms typically undergo external fertilization, where gametes are released into the water, and development is indirect with free-swimming larvae.

### Step 3: Conclusion
Based on the analysis, the statement that is **not a characteristic feature of phylum Echinodermata** is: "Fertilization is internal; development is indirect with free-swimming larvae." This is the incorrect statement.

### Final Answer
The statement that is not a characteristic feature of phylum Echinodermata is: **"Fertilization is internal; development is indirect with free-swimming larvae."**

---