Prolactin stimulates mammary gland growth and development in mammals and regulates salt and water balance in freshwater fish. Many scientists think that its wide range of functions among many organisms indicates that prolactin:.

Prolactin

Explanation:

Prolactin is a hormone that primarily promotes lactation (breast milk production) in mammalsIt is also responsible for a number of other functions and systems, for example it regulates behavior, the immune system, metabolism, reproductive systems, and many different bodily fluidsAll this makes it a crucial hormone for overall health and well-being, for both men and womenThe principal action of prolactin in fishes is freshwater osmoregulation, although it has also been implicated in reproduction, behavior, growth, and immunoregulation

Because of this wide range of functions, prolactin is considered an evolutionary conserved hormone    

The hawk receives 0.1% energy from the caterpillar although the caterpillar gets eaten by another bird smaller than the hawk first