Final answer:
The part of the bird feather shaft closest to the bird's body that is hollow and does not contain vanes is known as the calamus. It acts as an anchor and lacks the barbs and barbules found on the rest of the feather. Feathers serve various functions, including flight and insulation, critical for a bird's survival.
Step-by-step explanation:
The part of the bird feather shaft closest to the bird’s body that is hollow and does not contain any vanes is known as the calamus or quill. This part of the feather anchors it to the bird's skin, making it an integral component for attachment. Unlike the rest of the feather, the calamus does not have barbs or barbules; it serves as the base from which the rest of the feather, including the central shaft known as the rachis and the vane composed of interlocking barbs and barbules, develops.
Bird feathers are incredibly specialized structures with different types serving various purposes, such as flight, insulation, or showing off during mating displays. Flight feathers, including the primary and secondary feathers, are critical for the dynamics of flight, providing lift and thrust. With their central role in achieving and maintaining flight, they have evolved to become strong yet lightweight. In contrast to flight feathers, down feathers lack interlocking barbules, which makes them soft and fluffy, ideal for insulation to retain warmth. All of these features are essential adaptations that contribute to a bird’s ability to fly and regulate body temperature.