Question

Which of the following is a characteristic feature of fishes?
A. Tail and venous heart
B. Venous heart and gills
C. Epidermal scales and tail
D. Epidermal scales and gills

Answer 1

Hint: Fishes are the gill-bearing aquatic living animal. It’s a vertebrate that belongs to the phylum Chordata. All fish have some common evolutionary characteristics that help them to survive in the water.

Complete answer:
Fish is an animal that belongs to the class of vertebrate and phylum of Chordata. They are gill-bearing aquatic creatures which are cold-blooded. For the requirement of their survival, they have introduced some special characteristics.
In fishes, the heart is a 2-chambered heart with an atrium and a ventricle. The heart of fish pumps out deoxygenated blood, and later blood is oxygenated by the gills and spreads to the different body parts from where deoxygenated blood is returned to the heart. As the heart of fish pumps deoxygenated blood therefore it is called a venous heart.
For breathing under the water, fish have developed special organs which are known as gills. It is present on both the side of the body just behind the head which is composed of thousands of capillaries, or tiny blood vessels. This organ helps in the absorption and filtration of oxygen.

Hence, the correct answer is option (B).

Additional information:
All fishes are cold-blooded or ectothermic organisms. Due to this feature, the fishes are unable to regulate the temperature of their body. They depend on the outside environment for the purpose of the regulation of their body temperature. The presence of scales on the outer surface of the body is one of the most important characteristics of the fish. These scales provide them protection to the inner body, and also helps in smooth movement underwater. In the fish, there are a number of fins found. Some of them are single while some are paired. With the help of these fins, they can move forward under the water. Fins also help to balance their body and in rolling over. It also directs the path of their move.

Note: Fish are an aquatic living animal that belongs to the class of vertebrate and phylum of Chordata. Fishes have some distinct characteristics which have been adopted by them for survival in the water domain. They are a cold-blooded animal with scales and fins. They have a special type of heart with two chambers that pump deoxygenated blood. They also develop a special organ which is the gill as the organ of respiration.