Which of the following statements about cyclostomes is correct?
Cyclostomes (e.g., lampreys and hagfish) are jawless fishes that act as ectoparasites on other fishes.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Phylum Porifera and Cnidaria
#jawless fishes
3 public questions tagged with this topic.
Filter questions
Jawless fishes lack
Jawless fishes retain ancestral craniate morphology lacking innovations of gnathostomes. Most conspicuously they lack paired pectoral and pelvic fins that provide stabilization, braking and maneuvering in cartilaginous and bony fishes. Instead, locomotion depends on median dorsal and caudal fins plus body undulation creating anguilliform waves. Additional primitive characters include absence of true scales in hagfishes, cartilaginous cranium, single nostril and persistence of notochord. Gill basket supports branchial structures. Absence of paired fins reflects evolutionary stage predating appe
Ref: NCERT Class 11 Biology, Chapter 4: Cyclostomata; Brusca & Brusca, Chapter 24, Agnatha Paired Fins
Jawless fishes belong to class
Class Agnatha includes extant jawless craniates, representing earliest diverging vertebrate lineage lacking jaws derived from mandibular branchial arch, also lacking true paired appendages, dentine and bone in many forms. Characteristics include persistent notochord surrounded by arcualia, single median nostril in lampreys, multiple gill pouches opening separately, keratinized tooth-like structures and cartilaginous skeleton. Modern examples are Petromyzon lamprey and Myxine hagfish. Chondrichthyes, Osteichthyes and extinct Placodermi are jawed gnathostomes. Agnatha thus serves as stem group c
Ref: NCERT Class 11 Biology, Chapter 4: Cyclostomata Agnatha; Campbell Biology, 12th ed., Chapter 34