The enzymes that act inside the small intestine are amylase, protease, and lipase. Amylase acts on starch and breaks it down into small carbohydrate molecules. Protease acts on proteins and breaks them down into amino acids. Lipase breaks down dietary fats into smaller molecules called fatty acids and glycerol.
Sandhill Cranes mate for life, choosing their partners based on dancing displays. Displaying birds stretch their wings, pump their heads, bow, and leap into the air. Although each female usually lays two eggs, only one nestling typically survives to fledge.
Crayfish reproduce sexually and are capable of regeneration. Crayfish are either male or female, the males being the larger of the two. Usually mating occurs in autumn or spring, however the females can store the sperm from a fall mating until the spring when the eggs are fertilized and laid.