pennated

Pennated refers to a feather that has a well-defined shaft and barbs that are attached along its length. The barbs are typically interlocking, forming a continuous vane. This structure is characteristic of contour feathers, which provide insulation and streamline the bird's body, and flight feathers, which are essential for aerodynamics. In contrast, down feathers, which are primarily for insulation, have a fluffy structure with unbarbed or loosely barbed filaments extending from a short quill. The arrangement of barbs and barbules in a pennated feather creates a strong yet flexible surface that can withstand the stresses of flight. This complex and organized structure is a key evolutionary adaptation for avian locomotion and thermoregulation. The term pennated is derived from the Latin word "penna," meaning feather.