Why does this introduction seem incomplete? Identify the known, unknown, question/purpose, and experimental approach. Are these elements clearly identifiable? Why or why not?
The carotenoid astaxanthin is a red pigment that occurs in specific algae, fish, crustaceans, and in some bird plumages (McGraw and Hardy, 2006). Astaxanthin is an antioxidant and commonly is used as a natural food supplement, food color, and anticancer agent among other disease preventative measures.
Like many carotenoids, astaxanthin is a colorful, fat/oil-soluble pigment, providing a reddish and pink coloration (2). Whereas in certain bird species, all adult members display carotenoid containing feathers rich in color, many gulls and terns, which normally have white feathers, display an abnormal pink tinge (or flush) in various degrees across their populations (McGraw and Hardy, 2006). It has been suggested that this pink tinge arises during feather growth when these birds ingest abnormally high quantities of astaxanthin, which often occurs close to salmon farms (McGraw and Hardy, 2006). However, the exact relationship between astaxanthin and plumage is not fully understood. Here we examine this relationship in more detail and discuss its implication.