An enchinoderms which can both creep and swim actively is

Options

A. Oreaster
B. Ophiothrix
C. Echinus
D. Cucumaria.

Answer

To solve the question of identifying an echinoderm that can both creep and swim actively, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: We need to identify an echinoderm that has the ability to both creep along the sea floor and swim in the water.

2. **Evaluate the Options**:
- **Option 1: Oreaster (Starfish)**: Starfish are known for their ability to creep on the sea floor using their tube feet. They do not have the capability to swim actively. Therefore, this option is incorrect.

- **Option 2: Ophiothrix (Brittle Star)**: Brittle stars have long, flexible arms that allow them to move in a snake-like fashion. They can both crawl along the substrate and swim by using their arms to propel themselves through the water. This makes Ophiothrix a suitable candidate for our answer.

- **Option 3: Echinus (Sea Urchin)**: Sea urchins primarily crawl on the sea floor and do not swim. Hence, this option is also incorrect.

- **Option 4: Cucumeria (Sea Cucumber)**: Sea cucumbers are known for their creeping movement on the sea floor and do not swim. Therefore, this option is incorrect as well.

3. **Select the Correct Answer**: After evaluating all options, the only echinoderm that can both creep and swim actively is **Ophiothrix**.

### Final Answer:
The echinoderm that can both creep and swim actively is **Ophiothrix**.

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