Question

endoskeleton of fishes are made up of cartilage and bone.classify the fishes as cartilaginous or bony: mandarin fish; flying fish; rohu; dog fish; sting fish; lion fish; sea horse

Answer 1

Cartilaginous fishes (Chondricthyes)

Bony fishes (Osteichthyes)

1.        Exclusively marine.

Marine & fresh water.

2.        Heterocercalcaudal fin.

Homocercalcaudal fin.

3.        Cartilaginous endoskeleton.

Bony endoskeleton

4.        Gill slitswithout operculum.

4 pairs of gillscovered by anoperculum on each side.

5.        Crescent (half moon) shaped ventral mouth

Terminal mouth

6.        Skin withplacoid scales. Teeth are modified placoid scales which are backwardly directed.

Scales are Cycloid, ctenoid etc.

7.        No air bladderso they have to swim constantly to avoid sinking.

Air bladder for buoyancy

8.        Sexes are separate. In males pelvic fins bearclaspers.

Sexes are separate. No claspers

9.        Internal fertilization.

Fertilisation external

10.     Many of themviviparous

Mostly oviparous

11.     E.g.Scoliodon(Dog fish),Pr