Question

Choose the correct option from the list which is not an example of cartilaginous fish:

• A. Sawfish
• B. Stingray
• C. Rohu
• D. Shark

Answer 1

The correct option is C

Rohu

The correct option is C.

Explanation of the correct option:

1. The rohu is a type of fish found in South Asian rivers that belongs to the carp family.
2. It has four pairs of gills covered on all sides by plates.
3. Fishes with cartilage make up the class Chondrichthyes.
4. Fish with cartilaginous gills have slits that allow them to access the ocean.
5. Rather than using their gills, cartilaginous fish may alternatively breathe through spiracles.
6. The fish can breathe without breathing in the sand because of these apertures, which allow them to lie down on the ocean floor and pull oxygenated water into the top of their heads.
7. Hence, rohu isn't a cartilaginous fish.

Explanation of the incorrect option:

Option A:

1. The family of rays known as sawfish, commonly referred to as carpenter sharks, is distinguished by a long, narrow, flattened rostrum, or snout extension, that is lined with pointed transverse teeth that are organized to resemble a saw.
2. Some species can grow to a length of around 7.6–7.7 meters, making them some of the largest fishes.

Option B:

1. Sea rays, a class of cartilaginous fish allied to sharks, include stingrays.
2. The eight families that make up this group are Hexatrygonidae, Plesiobatidae, Urolophidae, Urotrygonidae, Dasyatidae, Potamotrygonidae, Gymnuridae, and Myliobatidae.
3. They are categorized as belonging to the suborder Myliobatoidei of the order Myliobatiformes.

Option D:

1. Sharks are an elasmobranch fish species distinguished by their cartilaginous skeleton, five to seven-gill slits on the sides of the skull, and unfused pectoral fins.
2. The clade Selachimorpha includes modern sharks, which are the rays' sister group.

Final Answer: - Rohu is not an example of cartilaginous fish.