Final answer:
Members of Chondrichthyes differ from members of Osteichthyes by having a cartilaginous skeleton.
Step-by-step explanation:
Members of Chondrichthyes differ from members of Osteichthyes by having a cartilaginous skeleton. Chondrichthyes, which includes sharks, rays, and skates, have skeletons made of cartilage, while Osteichthyes, which includes most bony fish, have skeletons made of bone. Cartilage is a tough tissue that is flexible and provides support, allowing these fish to move efficiently through the water.