Question

Which of the following characters are absent in Shark but present in Rohu
1) Air bladder, Operculum
2) Placoid scales, 6 pairs of gills
3) Clenoid scales, cartilaginous endoskeleton
4) Bony endoskeleton. Notochord​

Answer 1

Explanation:

4)Bony endoskeleton

A shark skin is soft so it does not have bony endoskeleton

Answer 2

1) Air bladder , operculum are present in rohu but absent in shark

because shark belong to class Chondrichthyes and Rohu belong to Class Osteichthyes

following are the characteristics of both the classes

Class Chondrichthyes

1. Have cartilaginous endoskeleton and persistence of notochord throughout life .

2. separate gill slits without operculum

3. tough skin with minute placoid scale

4. Have to swim constantly to avoid sinking underwater due to nonavailability of air bladder

5. Marine

Class Osteichthyes

1.Have bony endoskeleton

2. contain  air bladder, which provides buoyancy and prevents sinking.

3.skin covered by bony dermal scales known as ctenoid scales.

4.contain four pairs of gills which are covered by operculum.

5. both freshwater and marine

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