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 small group of worms like marine animals with organ system level of organization."

- **Analysis:** This statement is correct. Hemichordata is indeed a small group of marine animals that exhibit an organ system level of organization.

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

- **Analysis:** This statement is incorrect. Echinodermata, which includes starfish and sea urchins, typically undergo external fertilization. The sperm and eggs are released into the water, where fertilization occurs.

### Step 3: Analyze the third statement
**Statement:** "Radula is mollusk's help in feeding."

- **Analysis:** This statement is correct. The radula is a unique feeding organ found in mollusks, often described as a tongue-like structure with tiny teeth.

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

- **Analysis:** This statement is also correct. Parapodia are fleshy protrusions found on the bodies of many aquatic annelids, and they assist in locomotion.

### Conclusion
After analyzing all the statements, we find that the incorrect statement is the second one: "Fertilization is usually internal in Echinodermata."

### Final Answer
The incorrect statement is: "Fertilization is usually internal in Echinodermata."

---