Compare and contrast the jawless and jawed fish. How do scientists think the jaw first evolved in fishes? Was the

evolution of the jaw related to feeding? What will be an ideal response?


Various studies suggest that the jaw originally evolved from the first two or three anterior gill
arches of jawless fish. The jaw evolution may have been related to respiration. By evolving
joints in the forward gill arches, jawed fish could open their mouths wider. This would mean
that they could pump more water past the gills, increasing the oxygen intake, every time they
opened their mouths.

Environmental & Atmospheric Sciences

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