A serious disadvantage of complexity in higher organisms is

The serious disadvantage of complexity in higher organisms is a high demand for food and energy. As organisms become more complex, their bodies require more energy to function properly. This energy is obtained from the food they eat, which means that more complex organisms need to consume larger amounts of food to meet their energy requirements. This demand for food and energy can be a disadvantage because it can limit an organism's ability to survive in environments where food is scarce or competition for resources is high. Additionally, the need for more energy can also make complex organisms more vulnerable to environmental stresses or changes, such as climate change or habitat loss.