Question: 139. All living members of the class Cyclostomata are:
(1) Free living
(2) Endoparasite
(3) Symbiotic
(4) Ectoparasite
Answer: Option (4)
Explanation:
Cyclostomata includes jawless fishes such as lampreys and hagfishes. Most living members of this class are ectoparasites. They attach to the body surface of other fishes using their sucker-like mouth and feed on the host’s body fluids. Therefore, the correct answer is ectoparasite.