Question

What is a bony fish?

Answer 1

Hint: Fishes can be classified on the basis of the nature of their skeletal system. They are divided further as a superclass into cartilaginous (Chondrichthyes) and bony (Osteichthyes) fishes.

Complete answer:
Bony fishes are those fishes which have its endoskeleton composed of bone tissues and bilaterally flattened. These types of fishes can be seen both in the marine and freshwater environment. This group of fishes can be divided as ray-finned and lobe-finned. They possess a comparatively more stable pattern of a cranial bone. The head and the pectoral girdle are covered with large dermal bones. They possess a sclerotic ring to balance the eyeball. The evolved species consists of swim bladders which help in balancing between sinking and floating. They are devoid of fin spines, and also have an operculum. These kinds of fishes are devoid of placoid scales but consist of overlapping ctenoid scales and mucus glands coating the body. The respiratory organ of all bony fishes is gills. They possess no spiracles. The fishes are primarily ectothermic or cold-blooded.
Fertilization takes place externally in most of the cases but can take place internally too. It is oviparous or egg-laying in nature. The major examples of bony fishes are Tuna, Salmon and Trouts.

Note: The other major class of fishes is cartilaginous fishes also known as Chondrichthyes, which has a skeleton made of cartilages. This kind of fish possess gill slits and breathe through spiracles rather than the usage of gills. This kind of fish is covered with placoid scales. Most of the fishes in this class are marine inhabitants; sharks fall into this class of fishes.