Every species on the planet has evolved to make the most of the space available to it. That's why some animals are at their best in the daytime, while others shine at night. Animals that are active during the day (or plants that bloom in daylight) are called diurnal. Animals that are active after dark are called nocturnal.
There are also two in-between groups. Crepuscular animals come out at twilight, at dawn or dusk. Cathemeral animals can be active during the day or at night, depending on things like temperature and food supply.
- DiurnalActive by day
- NocturnalActive at night
- CrepuscularActive at dawn & dusk
- CathemeralActive day or night
Diurnal Vs. Nocturnal Animals and Plants
The biggest difference between diurnal and nocturnal animals is simple: when they are awake and when they sleep. Diurnal animals are active during the day and sleep at night. Nocturnal animals do the opposite, they are active at night and spend the daytime resting.
Red Squirrel, busy in the daytime, curled up asleep at night.
Philippine Tarsier, those giant eyes come alive after dark.
The list of diurnal animals includes squirrels, elephants, gorillas, various birds of prey, insects like butterflies and bees, and even humans. On the other hand, the nocturnal animals' list is dominated by bats, owls, lemurs, flying squirrels, ocelot, moths, tarsiers, etc.
Most plants are diurnal. They rely on sunlight for energy, so their flowers open during the day and close at night. Nocturnal plants are different, their flowers stay shut all day and only open after dark. They do this to attract night pollinators like bats and moths, which only come out once the sun goes down.
Gazania, opens wide in sunshine, closes up at night.
Angel's Trumpet, stays shut by day, perfumes the night air.
Examples of diurnal plants include gazanias and Venice mallow. Examples of nocturnal plants include night phlox, moonflowers, and angel's trumpets. The word diurnal comes from the Latin word diurnus, meaning "of the day." The word nocturnal comes from the Latin word nocturnus, meaning "of the night." Some animals have evolved to become nocturnal in order to survive the harsh conditions in their native habitat.
Built for Day, Built for Night
Desert animals, for instance, only come out of their burrows after nightfall. The temperature in deserts is mostly unbearable during the day. Diurnal desert animals deal with the heat differently, they reduce their activity by resting in the shade during the hottest part of the day.
Eyes also work differently depending on the time of day an animal is active. The eyes of diurnal species are packed with cone-shaped cells. Cones are less sensitive to light, but they can detect color. Nocturnal species have eyes dominated by rod-shaped cells. Rods are much more sensitive to light, which makes it easier to see in the dark, but they cannot detect color. As a general rule, diurnal animals can see in color, while nocturnal animals are colourblind.
| Feature | ☀️ Diurnal (Day) | 🌙 Nocturnal (Night) |
|---|---|---|
| Active when? | During the daytime; sleeps at night. | At night; sleeps during the daytime. |
| Eye cells | More cone cells, need brighter light, but detect color. | More rod cells, very sensitive to light, no color. |
| Color vision | Generally see in color. | Generally color-blind. |
| Example animals | Squirrels, elephants, gorillas, butterflies, bees, humans. | Bats, owls, lemurs, flying squirrels, ocelot, moths, tarsiers. |
| Example plants | Gazania, Venice mallow, flowers open by day. | Night phlox, moonflower, angel's trumpet, flowers open at night. |
| Name comes from | Latin diurnus, "of the day". | Latin nocturnus, "of the night". |
Frequently Asked Questions
What is the difference between diurnal and nocturnal animals?
Diurnal animals are active during the daytime and sleep at night, while nocturnal animals are active at night and sleep during the day. The differences go further than that, though: their eyes, senses, and survival tricks are all tuned to either daylight or darkness.
Are there animals that are neither fully diurnal nor nocturnal?
Yes. Crepuscular animals are active during twilight (at dawn or dusk) while cathemeral animals can be active during the day or the night, depending on factors like temperature, the moon, or how much food is around.
Why can nocturnal animals see in the dark but not see color?
Nocturnal eyes are packed with rod-shaped cells, which are very sensitive to light but cannot detect color. Diurnal eyes have more cone-shaped cells, which need brighter light but can see color. That is why most nocturnal animals are color-blind while most diurnal animals see in color.
Are plants diurnal or nocturnal too?
Both. Most plants are diurnal, their flowers open in the daytime to use sunlight. A few are nocturnal: flowers like moonflowers and angel's trumpets stay shut all day and open at night to attract night pollinators such as bats and moths.
Can an animal switch between diurnal and nocturnal?
Some can. The subterranean mole rat (Spalax ehrenbergi), for example, is diurnal in winter but switches to nocturnal behavior in summer to avoid the heat.
Nocturnal Animals' Special Senses
On top of their rod-packed eyes, nocturnal animals have specially adapted eyesight to help them see in the dark. Their eyes are bigger in proportion to their head and body, and their cornea is larger than that of diurnal species. You can clearly see this in tarsiers and certain species of owls.
Nocturnal animals also have a very well-developed sense of smell and hearing. Species like bats and owls use these senses to move around and hunt in pitch-dark surroundings.
Day or Night? Take the Quiz!
5 quick questions. Can you sort the day creatures from the night creatures?
Sharing Day and Night
Remember, it's all about making the most of available niches. Most birds of prey are diurnal, so it makes sense for rodents to become nocturnal to avoid them. This arrangement also benefits owls. Owls are among the few nocturnal birds of prey, so they have plenty of rodents to eat and very little competition from other predators, since most other birds of prey are only active during the day.
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