Question

Which of the following are the characteristic features of Pisces?
A. The skin is covered with scales/plates.
B. They obtain oxygen dissolved in water by using gills
C. Both A and B
D. They obtain oxygen dissolved in water by using lungs

Answer 1

Hint: Pisces belong to the Chordata phylum. They belong to the subdivision Vertebrata or Craniata. Vertebrates are characterized by a notochord that changes to the backbone and skull. They are further classified as Gnathostomata which means organisms with jaws present. Pisces contains almost all fishes.

Complete answer: Pisces is a superclass of the Gnathostomata. Some special features of Pisces are as follows –
Pisces have a body that is covered with scales or plates all over on their skin or tegument. Pisces have four kinds of scales on their body. These four types of scales are as follows –
a. Cycloid scales – These are the circular kinds of scales. They are usually found in bony fishes or Osteichthyes.
b. Ctenoid scales – These are the rectangular kind of scales. They are usually found in bony fishes or Osteichthyes.
c. Ganoid scales – These are the pointed or diamond-shaped scales. They are usually found in bony fishes or Osteichthyes.
d. Placoid scales – These are the plate-like scales. They are usually found in cartilaginous fishes or Chondrichthyes.

The body of Pisces is streamlined to cut water. They have fins to facilitate swimming and locomotion. Pisces usually have one pair dorsal, one pair ventral, one pair pectoral, one pair pelvic, and a single caudal fin. However, fins are present in other mammals like whales and dolphins too that swim.
The respiration in fishes is with the help of gills only except the Lung fishes. Thus, based on the above information that the characteristic features of Pisces are that their skin is covered with scales/plates, and they obtain oxygen dissolved in water by using gills.
Hence, the correct answer is option (C).

Note: There are three kinds of Lung fishes. These are –
1. African LungFish – Also known as the Protopterus. It is a freshwater fish. It has two well-developed lungs and poorly developed gills.
2. American LungFish – Also known as the Lepidosiren. It is a freshwater fish. It has two less developed lungs and comparatively better-developed gills.
3. Australian LungFish – Also known as the Neoceratodus. It is a freshwater fish. It has a single poorly developed lung and comparatively far better-developed gills.