Question

Jawless, exclusive marine bottom dwelling ectoparasites with cartilaginous vertebral column are grouped under the class:

• A. Cephalochordata
• B. Urochordata
• C. Osteichthyes
• D. Cyclostomata

Answer 1

The correct option is D

Cyclostomata

Sub-phylum Vertebrata is classified into two divisions based on the presence or absence of jaws - Agnatha and Gnathostomata. Division Agnatha includes jawless vertebrates, and includes only one class - Cyclostomata. They are thus, the only class of jawless vertebrates. All living members of this class are ectoparasites on some fishes. They have a sucking and circular mouth without jaws. Examples include Petromyzon (lamprey) and Myxine (hagfish). Urochordata and Cephalochordata are sub-phyla under Phylum Chordata, and Osteichthyes is a class under Superclass Pisces.