Question 50

Sharks and rays have vertebrae but lack a bony skeleton.

Sharks and rays are classified as cartilaginous fish, which means they possess a vertebral column made of cartilage rather than bone. This characteristic distinguishes them from bony fish and illustrates their unique evolutionary path.

A) Birds are the only species that produce eggs with shells.

This statement is incorrect because while birds do produce eggs with shells, reptiles and some species of fish also lay eggs with similar protective structures. Thus, birds are not the only group with this reproductive trait.

B) Amphibians are four-limbed species but lack a bony skeleton.

This option is misleading as amphibians are indeed four-limbed (tetrapods), but they possess a bony skeleton. The skeletal structure of amphibians is well-developed and includes bones that support their limbs and body.

C) Sharks and rays have vertebrae but lack a bony skeleton.

This statement accurately describes sharks and rays, which are known for their cartilaginous structures instead of a bony skeleton. This evolutionary adaptation allows for flexibility and buoyancy in their aquatic environment.

D) Only species with hair produce amniotic eggs.

This statement is incorrect because amniotic eggs are produced by a variety of species, including reptiles and some birds, which do not possess hair. Therefore, this claim does not hold true across all relevant taxa.

Conclusion

The correct answer, C, is definitively accurate in describing the unique anatomical structure of sharks and rays. All other options present incorrect or misleading information regarding the characteristics of the respective groups, thereby failing to represent the evolutionary biology of these organisms accurately.