Select the distinguishable characters of ophiura from balanoglossus

Options

A. Has an endoskeleton of calcareous ossicles
B. Has water vascular system
C. Is radially symmetrical
D. All of the above

Answer

To differentiate between Ophiura and Balanoglossus, we need to analyze their distinct characteristics based on their classifications and anatomical features.

### Step-by-Step Solution:

1. **Identify the Organisms**:
- Ophiura is commonly known as the serpent star and belongs to the phylum Echinodermata.
- Balanoglossus is known as the acorn worm and belongs to the phylum Hemichordata.

2. **Examine the Endoskeleton**:
- Ophiura has an endoskeleton made up of calcareous ossicles, which are small calcium carbonate structures.
- Balanoglossus does not possess a calcareous endoskeleton; instead, it has a more flexible body structure.

3. **Assess the Water Vascular System**:
- Ophiura has a well-developed water vascular system, which is a characteristic feature of echinoderms.
- Balanoglossus does not have a water vascular system; instead, it has a different type of coelomic system.

4. **Consider Symmetry**:
- Ophiura exhibits radial symmetry, meaning it can be divided into similar halves through multiple planes.
- Balanoglossus, however, shows bilateral symmetry, which means it can only be divided into two similar halves along one plane.

5. **Conclusion**:
- Based on the analysis, the distinguishing characters of Ophiura from Balanoglossus are:
- Ophiura has an endoskeleton of calcareous ossicles.
- Ophiura has a water vascular system.
- Ophiura is radially symmetrical.
- Therefore, the correct answer is **"All of the above"**.