Question

fishes are made up of cartilage. give reason

Answer 1

Answer:

so they can swim easily in water

Answer 2

Answer:

The skeleton of the fish is made of either cartilage (cartilaginous fishes) or bone (bony fishes). The fins are made up of bony fin rays and, except for the caudal fin, have no direct connection with the spine. They are supported only by the muscles.

Explanation:

The Chondrichthyes are considered cartilaginous fishes because the long endoskeleton elements called bones in other vertebrates are made of cartilage instead.  In contrast to the Chondrichthyes fishes, most of the skeleton of bony fish becomes calcified during development.