Which of the following are the most primitive fishes?
a) cyclostromes
b) chondrichthyes
c) osteichthyes
d) both b and c
Explanation: also called jawless fishes. They have circular mouth
Which of the following is/are true about cyclostromes (agnatha) fishes?
a) these fishes have long eel like body
b) skin is naked without scales
c) they lack paired fins (appendages)
d) all of these
How many pairs of gills are found in cyclostromes (jawless fish)?
a) three
b) five
c) seven
d) nine
Explanation: Each pair open separately to the outside and are not covered with operculum
Which of the following is/are the characteristic fishes belongs to class agnatha?
a) their skeleton is of lower grade, fibrous cartilage
b) they do not posses stomach because of their parasitic way of life
c) mouth is adapted for sucking and sexes are separate
d) all of these
Class chondrichthyes has fishes commonly called……..
a) jawless fish
b) cartilaginous fish
c) bony fish
d) primitive fish
Explanation: their skeleton is made of cartilage
Which of the following is/are the characteristic feature/s of chondrichthyes?
a) they have streamlined body
b) they live in marine environment
c) their mouth is ventral
d) all of these
