Which of the following is not a characteristic feature of Hemichordates?

Options

A. Exclusively marine
B. Excretion by proboscis gland
C. Notochord present only in anterior half of body
D. Respiration by gills

Answer

To determine which of the following is not a characteristic feature of Hemichordates, let's analyze the options based on known characteristics of this group.

### Step-by-Step Solution:

1. **Identify the Characteristics of Hemichordates**:
- Hemichordates are primarily marine organisms.
- They exhibit a body structure that includes a proboscis, collar, and trunk.
- They possess an open circulatory system.
- Excretion occurs through the proboscis gland.
- They have separate sexes.

2. **Evaluate the Options**:
- **Option 1: Exclusively marine** - This is a characteristic feature of Hemichordates, as they are found only in marine environments.
- **Option 2: Excretion through proboscis gland** - This is also correct, as Hemichordates excrete waste through the proboscis gland.
- **Option 3: Notochord present only in the interior half of the body** - This statement is misleading. Hemichordates do have a structure similar to a notochord, but it is not accurately described as being present only in the interior half of the body. Instead, it is more accurately referred to as a "stomochord," which is located in the proboscis region.
- **Option 4: Respiration by gills** - This is true, as Hemichordates respire through gill structures.

3. **Conclusion**:
- The option that is not a characteristic feature of Hemichordates is **Option 3: Notochord present only in the interior half of the body**.

### Final Answer:
**The option that is not a characteristic feature of Hemichordates is: Notochord present only in the interior half of the body.**

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