(a) Stream lined body
(b) Four pair of gills
(c) Air bladder is present
(d) In males pelvic fins bear claspers (e) Two chambered heart
(f) Fertilization is usually external
How many statements are correct for the members of class osteichthyes?

Options

A. one
B. two
C. five
D. six

Answer

To determine how many statements are correct for the members of class Osteichthyes (bony fishes), we will analyze each statement one by one:

1. **Streamlined body**:
- Osteichthyes, or bony fishes, typically have a streamlined body shape that aids in swimming efficiently through water.
- **Conclusion**: This statement is correct.

2. **Four pair of gills**:
- Bony fishes possess gills for respiration, and they have four pairs of gills.
- **Conclusion**: This statement is correct.

3. **Air bladder is present**:
- Many bony fishes have an air bladder (swim bladder) that helps them maintain buoyancy in water.
- **Conclusion**: This statement is correct.

4. **In males, pelvic fins bear claspers**:
- Claspers are specialized structures found in male Chondrichthyes (cartilaginous fishes like sharks and rays) for reproduction. Osteichthyes do not have claspers; this statement refers to Chondrichthyes.
- **Conclusion**: This statement is incorrect.

5. **Two chambered heart**:
- Bony fishes have a two-chambered heart, consisting of one atrium and one ventricle, which is typical for fish.
- **Conclusion**: This statement is correct.

6. **Fertilization is usually external**:
- Most bony fishes reproduce by external fertilization, where eggs and sperm are released into the water.
- **Conclusion**: This statement is correct.

Now, let's summarize the findings:
- Correct statements: 1 (streamlined body), 2 (four pair of gills), 3 (air bladder is present), 5 (two chambered heart), and 6 (fertilization is usually external).
- Incorrect statement: 4 (in males, pelvic fins bear claspers).

**Total correct statements**: 5

**Final Answer**: 5 statements are correct for the members of class Osteichthyes.