Question

In one of the following fish, the dorsal fin is modified into suckers
a. Torpedo
b. Echeneis
c. Hippocampus
d. Neoceratodus

Answer 1

Dorsal fin of a fish is a stabilizing fin which is located on the top of a fish (as well as some marine mammals). It is mainly used to make sure the fish is stabilized while swimming and help the fish while it moves through turns and stops.

Complete answer:
- The fins are the most distinguished anatomical features of a fish.
- The fins are mainly composed of bony spines or rays protruding from the body with skin covering the fins and joining them together.
- Other than the tail or the caudal fin the fish fins do not have a direct connection with the spine and they are completely supported only by the muscles. The main function is to help the fish to swim.
- Suckerfish or the Echeneis form the ray-finned fishes. They can grow up to 110 cm. The dorsal fin is modified into an oval shaped sucking disc. They are found in tropical and warm temperate climates.

Hence, the correct answer is option (B).

Note: The dorsal fins help in increasing the lateral surface of the body while the fish swims, thus providing stability even though the drag increases while the fish swims. No bones or cartilage is present in the dorsal fin and flukes of the dorsal fin, instead, they're made up of dense connective tissue. Longitudinal muscles in the back and caudal peduncle move the flukes up and down. The dorsal fin is a median fin located on the dorsal side of the fish.