Marine bony fish have body fluids hypotonic to sea water and tend to lose water from the body through
(a) Gill membrane (b) Oral membrane ( c) Anal membrane

Options

A. (a) only
B. (a), (b) and (c)
C. (a) and (c) only
D. (b) and (c) only

Answer

To solve the question regarding how marine bony fish lose water from their bodies, we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Hypotonic Solutions**:
- Marine bony fish have body fluids that are hypotonic compared to seawater. This means that the concentration of solutes (like salts) in their body fluids is lower than that in seawater.

2. **Water Loss Mechanism**:
- Because their body fluids are hypotonic, marine bony fish tend to lose water to the surrounding seawater. This is a result of osmosis, where water moves from an area of lower solute concentration (inside the fish) to an area of higher solute concentration (seawater).

3. **Identifying the Membranes**:
- The question provides three options: gill membrane, oral membrane, and anal membrane. We need to determine through which of these membranes marine bony fish primarily lose water.

4. **Gill Membrane**:
- The gill membranes are highly permeable and are involved in gas exchange. They also play a significant role in osmoregulation, allowing for the loss of water and the excretion of excess salts.

5. **Oral and Anal Membranes**:
- The oral membrane (mouth area) and anal membrane (anus) can also be involved in water loss, but they are not the primary sites for osmoregulation in marine bony fish.

6. **Conclusion**:
- The primary method by which marine bony fish lose water is through the gill membranes. Therefore, the correct answer to the question is (a) Gill membrane.

### Final Answer:
Marine bony fish have body fluids hypotonic to seawater and tend to lose water from the body through (a) Gill membrane.

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