The living manta ray and the fossil shark both have skeletons made of cartilage because:
1. Cartilage is lighter than bone, which is beneficial for aquatic animals like manta rays and sharks. This lighter skeleton helps them stay buoyant in water, making it easier for them to swim and maneuver efficiently.
2. Cartilage is more flexible than bone, allowing these animals to move swiftly and gracefully through the water. This flexibility is crucial for their survival as it enables them to navigate their environment, catch prey, and escape predators more effectively.
3. Additionally, a cartilaginous skeleton is more resistant to damage from the pressure changes experienced at different depths in the ocean. This feature is advantageous for deep-sea dwellers like sharks and rays, helping them withstand the challenges of their underwater habitats.
