Q.Write four salient features of cyclostomes.

Cyclostomes (class Cyclostomata, e.g. Petromyzon and Myxine) are the most primitive living chordates, marked by a jawless sucking mouth, an eel-like scaleless body, and a persistent notochord.

Four salient features of cyclostomes:

1. Jawless mouth: They lack true jaws; the mouth is a circular, sucking aperture armed with horny (keratinized) teeth, used to attach to and rasp the flesh of host fish.
2. Body form: The body is elongated and eel-like, and lacks paired appendages (no pectoral or pelvic fins), unlike jawed fishes.
3. Endoskeleton: The endoskeleton is entirely cartilaginous; the notochord persists throughout life and is not replaced by a vertebral column, so true vertebrae are absent. …