- A Cyclostomata have jaws, Chondrichthyes are jawless in general practice as commonly described
- B Cyclostomata are jawless and ectoparasitic, Chondrichthyes have jaws and are mostly predaceous
- C Cyclostomata have a bony endoskeleton, Chondrichthyes have a cartilaginous one in most textbook accounts
- D Cyclostomata live mainly in deserts, Chondrichthyes live mainly in rivers during normal conditions
Correct answer: B. Cyclostomata are jawless and ectoparasitic, Chondrichthyes have jaws and are mostly predaceous
Explanation: Cyclostomata (e.g., Petromyzon, Myxine) are jawless vertebrates, often ectoparasitic on other fishes, with a cartilaginous cranium and vertebral column. Chondrichthyes (sharks, rays) have jaws and are mostly predaceous marine fishes.
Concept context
Phylum-level classification of the animal kingdom from Porifera to Chordata, based on body symmetry, coelom, and segmentation. One of the most example-heavy chapters for NEET.