Question

Classify and explain any two different kinds of fishes with suitable examples.

Answer 1

Different types of fish:

The two different types of fish are - Osteichthyes and Chondrichthyes. The two types of fishes are explained below in detail.

1. Osteichthyes:

1. The word ‘Osteichthyes’ is derived from the Greek word ‘osteon’ means ‘bones’ and ‘ichthys’ means ‘fish’.
2. These are marine and freshwater fishes.
3. Some examples are rohu (Labeo), mandarin fish (Synchiropus), sea horse (Hippocampus), lion fish (Pteroisvolitans), flying fish (Exocoetus), lungfish (Protopterus), climbing perch (Anabas).

Characteristics:

1. The body is spindle-shaped.
2. Mouth is terminal in position.
3. Tail fin is homocercal.
4. Skin is either covered with cycloid scales or ctenoid scales.
5. These animals excrete ammonia and hence are called ammonotelic animals.
6. They are cold-blooded animals.
7. They lay eggs.

2. Chondrichthyes:

1. They are marine and are large-sized animals.
2. The body is either spindle-shaped or dorsoventrally flattened.
3. It includes Indian shark (scoliosis), hammer-headed shark (Sphyrna), electric ray (torpedo), stingray (trygon), sawfish (Pristis), ratfish (chimaera).

Characteristics:

1. Mouth is ventral in position.
2. The skin is covered with placoid (tooth-like) scales.
3. The streamlined body helps in swimming and the tail helps in propulsion.
4. The skeleton is completely cartilaginous.
5. The tail is heterocercal.
6. Respiration takes place through the gills.
7. They have fins for swimming and balance.