The more specialized of a function a cell performs, the less likely it is for the cell to change jobs within an organism. But some cells have unspecialized functions and are able to adapt to the changing needs of the body. For example, in mammals such cells include bone marrow cells, which are responsible for producing different types of cells in the blood—in all, red blood cells and five types of white blood cells (for more about blood cells, see the chapter “Anatomy: Animals Inside”). Other organisms, including slime molds of the kingdom Protista, also have cells that are capable of drastically changing their function, allowing them to change from single-celled amoebas to multicellular, reproductive spore producers.