What is unique in the blood circulation of Herdmania?

Options

A. Its slow beat
B. To generate high blood pressure
C. Its immense cardiac output
D. Its ability to reverse the direction of blood flow when heart contracts

Answer

### Step-by-Step Solution:

1. **Identify the Organism**: The question asks about Herdmania, which is an organism that belongs to the phylum Chordata.

2. **Classify the Organism**: Herdmania is classified under the subphylum Urochordata, specifically within the group known as Ascidians.

3. **Understand Blood Circulation**: In Herdmania, the blood circulation system is well-developed. It features a muscular tubular organ that functions as the heart.

4. **Unique Feature of Blood Circulation**: A unique aspect of blood circulation in Herdmania is the phenomenon of "reversal of peristalsis." This means that when the heart contracts, the direction of blood flow can change.

5. **Evaluate Options**: The question may provide multiple-choice answers. The unique feature identified is the ability to reverse the direction of blood flow during heart contractions, which is not common in other organisms.

6. **Select the Correct Answer**: Based on the analysis, the correct answer is that Herdmania has the unique ability to reverse the direction of blood flow when the heart contracts.

### Final Answer:
The unique feature in the blood circulation of Herdmania is its ability to reverse the direction of blood flow when the heart contracts due to the reversal of peristalsis.

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