Select the incorrect statement.

Options

A. Phylum Hemichordata consists of a small group of worm-like marine animals with organ-system level of organisation.
B. Fertilization is usually internal in Echinodermata.
C. Radula in mollusca helps in feeding.
D. Parapodia is found in aquatic annelids.

Answer

To solve the question of selecting the incorrect statement, we will analyze each statement provided in the video transcript step by step.

### Step 1: Analyze the first statement
**Statement:** "Phylum Hemichordata consists of a small group of worm-like marine animals with organ system level of organization."

**Analysis:**
- Hemichordata is indeed a phylum that includes worm-like marine animals.
- They have an organ system level of organization, bilateral symmetry, are triploblastic, and are coelomate.
- **Conclusion:** This statement is true.

### Step 2: Analyze the second statement
**Statement:** "Fertilization is usually internal in Echinodermata."

**Analysis:**
- Echinoderms, such as starfish and sea urchins, typically exhibit external fertilization, where eggs and sperm are released into the water for fertilization.
- **Conclusion:** This statement is incorrect.

### Step 3: Analyze the third statement
**Statement:** "Radula in Mollusca helps in feeding."

**Analysis:**
- The radula is a specialized feeding organ found in many mollusks, which is used to scrape food particles off surfaces.
- **Conclusion:** This statement is true.

### Step 4: Analyze the fourth statement
**Statement:** "Parapodia is found in aquatic annelids."

**Analysis:**
- Parapodia are lateral appendages found in many aquatic annelids (e.g., Nereis), which aid in swimming and locomotion.
- **Conclusion:** This statement is true.

### Final Conclusion
Based on the analysis of all statements, the incorrect statement is the second one: "Fertilization is usually internal in Echinodermata."