One of the following character is not unique to phylum arthropoda

Options

A. Chitinous exoskeleton
B. Jointed appendages
C. Malpighian tubules for excretion
D. Closed type of blood vascular system

Answer

To solve the question "One of the following characters is not unique to phylum Arthropoda," we need to analyze the characteristics associated with Arthropoda and identify which one is not exclusive to this phylum.

### Step-by-Step Solution:

1. **Identify the Characteristics of Arthropoda**:
- Arthropods are known for having an exoskeleton made of chitin.
- They possess jointed appendages (legs and other body parts).
- They have a unique excretory system that includes Malpighian tubules.
- Their circulatory system is typically open, meaning blood is not always contained within vessels.

2. **Analyze Each Characteristic**:
- **Exoskeleton made of chitin**: This is a unique feature of Arthropoda.
- **Jointed appendages**: This is also a defining characteristic of Arthropoda.
- **Malpighian tubules for excretion**: This is a unique characteristic of Arthropoda.
- **Closed circulatory system**: This is the key point. Arthropods generally have an open circulatory system, not a closed one. Closed circulatory systems are found in other phyla, such as Annelida (earthworms) and Chordata (vertebrates).

3. **Conclusion**:
- The characteristic that is **not unique** to phylum Arthropoda is the **closed circulatory system**. Therefore, the correct answer to the question is option number 4.

### Final Answer:
The characteristic that is not unique to phylum Arthropoda is the **closed circulatory system** (option number 4).