Question

Differentiate between cartilaginous fishes and bony fishes.

Answer 1

Hint:Fishes basically come under phylum chordata and division gnathostomata that means jaw bearing animals. Fishes are the gill bearing animal in which gills act as a respiratory organ as well as bearing fins that help in locomotion. Heart is two chambered with one auricle and one ventricle.

Complete answer:
 Fish covers almost half part of the population among vertebrates that shows the greater significance of fish among animals. They are poikilotherms (cold blooded animals). There are two classes of Pisces (fish)
->Chondrichthyes
->Osteichthyes

Class Chondrichthyes	Class Osteichthyes
These are commonly known as cartilaginous fishes. They are called so because of the presence of cartilaginous endoskeleton	These are commonly known as bony fishes. They are called so because of the presence of bony endoskeleton.
They are marine animals having streamlined bodies.	They are marine and freshwater animals with streamlined bodies.
Mouth is located ventrally.	Mouth is located mostly terminally.
Notochord (a dorsal hollow nerve cord and paired pharyngeal gill slits) is persistent throughout life.	They have four pairs of gills with operculum on each side.
Gill slits are separate and without operculum (gill cover).	Skin is covered with cycloid/ctenoid scales.
The skin is tough having minute placoid scales.	Air bladder is present which regulates buoyancy.
They have internal fertilization and many of them are viviparous.	They have external fertilization and mostly they are oviparous and development is direct.
Examples: Scoliodon(dog fish),Pristis(saw fish),Carcharodon(great white shark),Trygon(stingray).	Example: Marine- Exocoetus (flying fish) and Hippocampus (sea horse). Freshwater –Labeo (rohu), Catla (katla), Clarius (magur) Aquarium- Betta (fighting fish), Pterophyllum (angel)

Note:Some of the cartilaginous fishes have electric organs (example: Torpedo) and some possess poison sting (example: Trygon) which are helpful in defense and also for paralyzing and kill their prey.The blue whale known as giant and largest aquatic animal is not a fish; it is a mammal and belongs to the class mammalia of phylum chordata.