Opercula are absent in cartilaginous and jawless fishes and represent an evolutionary advancement seen in bony fish. how do opercula allow a bony fish to pass water over its gills while the fish remains statrionary? why would this be viewed as an adaptation?

Select the correct answer. which statement applies only to the axial skeleton, not the appendicular skeleton? a. it contains a pivot joint. b. it has muscles attached that work in pairs. c. it contains red bone marrow. d. it possesses fossa for bone articulation. e. it protects the heart and lungs.