Consider the following characteristic of fishes :-
(1) They have four pairs of gills which are covered by an operculum.
(2) They have air bladder which regulates buoyancy
(3) They are mostly viviparous and development is direct
(4) Their body is streamlined and covered with cycloid/ctenoid scales
Which of the above characteristics regarding bony fishes are correct?

Options

A. 1, 2 and 3
B. 3 and 4
C. 1, 2 and 4
D. 2 alone

Answer

To determine which characteristics regarding bony fishes are correct, let's analyze each statement step by step:

### Step 1: Analyze the first characteristic
**Statement:** They have four pairs of gills which are covered by an operculum.
**Analysis:** Bony fishes typically have five pairs of gills, not four. However, they do have an operculum that covers these gills. Therefore, this statement is partially correct but misleading as it incorrectly states the number of gills.

### Step 2: Analyze the second characteristic
**Statement:** They have an air bladder which regulates buoyancy.
**Analysis:** This statement is correct. Bony fishes possess a swim bladder (or air bladder) that helps them maintain buoyancy in the water.

### Step 3: Analyze the third characteristic
**Statement:** They are mostly viviparous and development is direct.
**Analysis:** This statement is incorrect. Most bony fishes are oviparous, meaning they lay eggs, and their development is typically indirect, involving a larval stage. Therefore, this statement is false.

### Step 4: Analyze the fourth characteristic
**Statement:** Their body is streamlined and covered with cycloid/ctenoid scales.
**Analysis:** This statement is correct. Bony fishes have a streamlined body shape that reduces water resistance, and they are covered with either cycloid or ctenoid scales.

### Conclusion
Based on the analysis:
- The first statement is misleading (incorrect number of gills).
- The second statement is correct.
- The third statement is incorrect.
- The fourth statement is correct.

Thus, the correct characteristics regarding bony fishes are the second and fourth statements.

### Final Answer
The correct characteristics regarding bony fishes are statements 2 and 4.

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