Which organisms are called primitive and how are they different from the so-called
A primitive organism or lower organism is the one which has a simple body structure and ancient body design or features that have not changed much over a period of time. An advanced organism or higher organism has a complex body structure and organization which they have acquired relatively recently. For example, an amoeba is more primitive as compared to a starfish. amoeba has a simple body structure and primitive features as compared to a starfish. Hence, an amoeba is considered more primitive than a starfish.