 Conceiving of physiological individuals as living agents, and supposing that all organisms are living agents but that there may be both parts and groups of organisms that are not, allows us to extend the visual summary introduced in  Figure 2.  Figure 3 depicts organisms as living agents but also contains regions for organs such as hearts and other constituent parts of organisms as living agents, as well as groups that may be living agents but not organisms (e.g., perhaps a coral reef).