A neuromuscular spindle is a spindle-shaped end organ in skeletal muscle. Afferent nerve fibers terminate and is sensitive to passive stretching of the muscle enclosing it.
Lungs take in gas from the Atmosphere, where the Oxygen is diffused into the blood cells, which take the Oxygen to different organs/places that need it. . .
Gills take in dissolved oxygen from the water, and then use diffusion like lungs.
C. birds and reptiles share a number of inherited characteristics