Question

The Chondrichthyes, like sharks and rays, are different from other fish in that:

M.M. 1

They have ossified ("bony") skeleton

They don't have a back bone

They do not have swim bladders

All of the above

​

Answer 1

Answer:

(C) They do not have swim bladders

Explanation:

Chondrichthyes

Chondrichthyes are a class of jawed fishes that have a cartilaginous skeleton. The class includes a diverse group of fish, including sharks, rays, skates, and chimeras. These are mostly marine fish.

Characteristics of Chondrichthyes

• These are mostly marine fish.
• They contain a pair of jaws. Their jaws are very powerful.
• Whale sharks are the second largest vertebrate and the largest fish. Some whale sharks are up to 15 meters long.
• The mouth is in the stomach.
• They contain a cartilaginous skeleton reinforced by calcium salts.
• Notochord is present throughout life.
• Most contain a heterocercal tail. The tail has two lobes, the upper lobe is elongated and the vertebrae extend into it, and the lower lobe is shorter, creating a distinct heterocercal tail.
• Small tooth-like structures called placoids cover the skin.

(A) They have ossified ("bony") skeleton

The above option is incorrect because chondrichthyes are cartilaginous fishes where the deposits of calcium salts provide strength to it. They don't have ossified or bony skeleton.

(B) They don't have a back bone

The above option is incorrect because they have a backbone.

(C) They do not have swim bladders

The above option is correct because chondrichthyes lack air or swim bladders so they swim actively to avoid sinking.

(D) All of the above

The above option is incorrect because option (A) and option (B) is incorrect.

Therefore, the correct option for the above question is (C) they do not have swim bladders.

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Answer 2

In this question, we are asked to choose the correct option from the given below.

• Option C is the correct answer i.e., They do not have swim bladders
• A class of jawed fish known as Chondrichthyes has a cartilaginous skeleton. Sharks, rays, skates, and chimeras are among the many fish in this class. Most of these are marine fish.
• Some of the characteristics of Chondrichthyes are-
• Most of these are marine fish.
• They have jaws on them. Their jaws have a lot of force.
• The second-biggest vertebrate and the largest fish are whale sharks. Some whale sharks can grow to a length of 15 meters.
• The stomach contains the mouth.
• They have a calcium salt-reinforced cartilaginous skeleton.
• The notochord is there all the time.
• The majority have a heterocercal tail. The heterocercal tail is distinguished by its two lobes, the top lobe of which is longer and into which the vertebrae extend.
• Placoid structures, which resemble little teeth, cover.

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