Question

List out the differences between class-Chondrichthyes and Class Osteichthyes.

Answer 1

Hint: Chondrichthyan (chondrichthyes class), also known as chondrichthyan, is any member of a large group of cartilaginous fish, including sharks, skates, rays and chimaeras. The class is one of the two great classes of living fish, the other being osteichthyans or bony fish.

Complete Answer:

Key features	Chondrichthyes	Osteichthyes
Other names	Also known as cartilaginous fish	Also known as bony fish
Habitat	They live in marine water. Occasionally some fishes enter freshwater	They live in both marine and freshwater.
Endoskeleton	It is made up of cartilage	It is made up of bones
Scale types	Small denticles called placoid scales cover up the body	Scales are ganoid and laptoid if the scales are present.
Size	They are larger in size	Comparatively the fishes are smaller in size
Mouth	The mouth is at the ventral side	The mouth is at the anterior tip.This is called as terminal mouth
Gills	5 to 7 pairs of gills are found	4 pairs of gills are present
Gill cover or operculum	The gills are not covered	On each side The gills are covered by operculum
Swim bladder	They are absent here	They have a swim bladder for buoyancy. It is also called as air bladder orgas bladder
Caudal fin	The lobes of fins are not equal, that is they have heterocercal caudal fins.	Both lobes are equal here and so they have homocercal fins.
Fertilization	Internal fertilization occurs.	The fertilization is external.
Excretory products	Urea is the excretory product.	Ammonia is the excretory product.
Feed	They are carnivorous.	They may be omnivorous, carnivorous, herbivorous, filter feeders or detritivorous.
Examples	Sharks, Skates and Rays	Tuna, Dolphins, salmon, Rohu, Seahorse etc.

Note: Fish are cold-blooded marine species that belong to the subphylum Vertebrata of phylum Chordata. To human beings, fish are very important because they have nutrients and micronutrients. For children's physical development, these nutrients are essential. In all stages of human life, it is also an important component of a balanced diet and controls many diseases. In many developed nations, they are an important source of income and jobs for citizens.