Question

Compare and contrast the internal anatomy of the shark and the bony fish. What are TWO major differences? Are these differences related to adaptation to different modes of life, or are they more likely to be related to genetic and developmental constraints?

Answer 1

Answer:

• Sharks are Cartilaginous Fishes that means their skeleton is made of cartilage and sharks belongs to Class Chondrichthyes. On the other hand, Bony fishes skeletons are composed primarily of bone tissues and bony fish belongs to Class Osteichthyes.
• Bony fish have ossified internal skeleton (made of calcified bone) and bony fish contains around 63 bones in their skull whereas shark have around 10 cartilaginous bones in their skull.
• Incase of bony fish, the vulnerable gill slits (single outer bony slit) are covered with protective bony plates (operculum) that also provides facial support whereas incase of sharks the gill slits are more in number (6-7 pairs) and are exposed and visible.
• In bony fish the upper jaw is attached to the skull whereas in shark the upper jaw rests below the skull and is not attached to the skull. This helps in independent movement of jaw incase of shark.

These differences are related to evolutionary benefits of cartilaginous skeleton as compared to bony tissues such as weight reduction, improve buoyancy, better flexibility as cartilage is softer and more flexible as compared to bone, more bite force. These adaptations provided sharks distinct advantage over bony fishes.