Question

Due to which one of the following characteristics, Scoliodon is called a dogfish?
a. Mouth
b. Snout
c. Carnivorous behaviour
d. Power of smell

Answer 1

Hint: Scoliodon is a marine shark commonly seen in the Bay of Bengal. It is distinguished from other fishes by having an elongated snout, depressed head and a compressed body.

Complete answer:
Scoliodon is a cartilaginous fish belonging to the class Chondrichthyes (cartilaginous fishes). It is a marine, carnivorous and predaceous fish. It has an elongated, spindle-shaped body tapered at the ends, making it a very fast swimmer.

The body is divisible into three parts namely head, trunk and tail.
- The head is dorsoventrally flattened and terminates anteriorly into a compressed snout.
- The trunk and tail are laterally compressed. Its body is covered by an exoskeleton made up of placoid scales.
- The mouth is located on the ventral side and is bound on both sides by jaws. Its protruded snout like mouth resembles the mouth of a dog.
- Due to this protruded snout, it is commonly known as ‘dogfish’.

So, the correct answer is B.

Note:
- The subclass Elasmobranchii comprises a large variety of cartilaginous fishes. To give a general idea of the class, the common example of the group, the dogfish, is selected as an introductory type.
- There are a number of genera of dogfishes found in different parts of the earth. The genus is represented by about nine species, of which four are very common in the Indian seas.
- The four Indian species of Scoliodon are: Scoliodon sorrakowah, S. palasorrah, S. dumerilii and S. walbeehm.