What is the term for organisms that are active at night?

The term for organisms that are active during the night is "nocturnal." Nocturnal animals have adapted to this lifestyle for various reasons, such as avoiding predators, reducing competition for food, and adapting to cooler temperatures during hot seasons. These adaptations often include enhanced night vision, improved sensory functions like hearing and smell, and behaviors that optimize their feeding and breeding activities in the absence of light.

In contrast, diurnal organisms are active during the daytime, typically capitalizing on sunlight for visibility and warmth. Crepuscular organisms are active during the twilight hours of dawn and dusk, which can provide advantages such as lower predation risk or specific feeding opportunities. Short day plants are a different category entirely, referring to plants that flower when daylight hours are shorter, unrelated to the activity patterns of organisms. Thus, nocturnal specifically designates those whose primary activities occur at night.