Nocturnality in the context of Night owl (person)

Lemurs (/ˈliːmərz/ LEE-mərz; from Latin lemurēs 'ghosts, spirits of the dead') are wet-nosed primates of the superfamily Lemuroidea (/ˌlɛmjʊˈrɔɪdiə/ LEM-yuu-ROY-dee-ə), divided into eight families and consisting of 15 genera and around 100 extant species. They are endemic to the island of Madagascar. Most existing lemurs are small, with a pointed snout, large eyes, and a long tail. They usually live in trees and are active at night.

Lemurs share resemblance with other primates, but evolved independently from monkeys and apes. Due to Madagascar’s highly seasonal climate, lemur evolution has produced a level of species diversity rivaling that of any other primate group.

Galagos /ɡəˈleɪɡoʊz/, also known as bush babies or nagapies (meaning "night monkeys" in Afrikaans), are small nocturnal primates native to continental, sub-Sahara Africa, and make up the family Galagidae (also sometimes called Galagonidae). They are considered a sister group of the Lorisidae.

According to some accounts, the name "bush baby" comes from either the animal's cries or its appearance. The Ghanaian name aposor is given to them because of their firm grip on branches.

The lion (Panthera leo) is a large cat of the genus Panthera, currently ranging only in Sub-Saharan Africa and India. It has a muscular, broad-chested body; a short, rounded head; round ears; and a dark, hairy tuft at the tip of its tail. It is sexually dimorphic; adult male lions are larger than females and have a more prominent mane that usually obscures the ears and extends to the shoulders.

The lion inhabits grasslands, savannahs, and shrublands. It is an apex and keystone predator, preying mostly on medium-sized and large ungulates. It is usually more diurnal than other wild cats, but when persecuted, it adapts to being active at night and at twilight. It is a social species, forming groups called prides. A lion pride consists of related females and cubs, and a few or one adult male who is unrelated to the females. Groups of female lions usually hunt together. Adult males often compete to keep or gain that membership in the pride.

Whiskers, also known as vibrissae (/vəˈbrɪsi/; sg. vibrissa; /vəˈbrɪsə/), are specialized sensory hairs that help most species of mammals sense their environment. Whiskers function as highly sensitive feelers that help mammals navigate the world in many different ways, including the detection of air currents and physical objects to aid in navigation, hunting, and spatial awareness. Whiskers can trigger reflexes to protect the eyes. Whiskers also play a significant role in the communication between individual animals in different species of mammals. They convey an animal's emotional state, essentially sending a message to other members of their species about what emotion they are feeling at the time. Whisker movement can be thought of as a form of language that animals use to silently communicate with the other animals around them.

Whiskers grow in clusters at various places around the body, including above the eyes, on the chin, on the forelegs, near the ears, and above the upper lip. Most mammals have whiskers, including all non-human primates, marsupials, and especially nocturnal mammals. Monotremes, however, lack them.

In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be part of a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and mimicry. Crypsis can involve visual, olfactory (with pheromones) or auditory concealment. When it is visual, the term cryptic coloration, effectively a synonym for animal camouflage, is sometimes used, but many different methods of camouflage are employed in nature.

The tapetum lucidum (Latin for 'bright tapestry, coverlet'; /təˈpiːtəm ˈluːsɪdəm/ tə-PEE-təm LOO-sih-dəm; pl.: tapeta lucida) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It reflects visible light back through the retina, increasing the light available to the photoreceptors (although slightly blurring the image).

The tapetum lucidum contributes to the superior night vision of some animals. Many of these animals are nocturnal, especially carnivores, while others are deep-sea animals. Similar adaptations occur in some species of spiders. Haplorhine primates, including humans, are diurnal and lack a tapetum lucidum.

In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal (active during dawn), vespertine/vespertinal (active during dusk), or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daytime and of night, respectively. Some crepuscular animals may also be active by moonlight or during an overcast day.

A number of factors affect the time of day an animal is active. Predators hunt when their prey is available, and prey try to avoid the times when their principal predators are at large. The temperature may be too high at midday or too low at night. Some creatures may adjust their activities depending on local competition.