Loris

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Loris
Gray slender lory (Loris lydekkerianus)

Gray slender lory ( Loris lydekkerianus )

Systematics
Superordinate : Euarchontoglires
without rank: Euarchonta
Order : Primates (Primates)
Subordination : Wet-nose primates (Strepsirrhini)
Partial order : Lori-like (Lorisiformes)
Family : Loris
Scientific name
Lorisidae
Gray , 1821

The Loris (Lorisidae or Loridae), also digested monkeys are a primate family from the group of wet proboscis monkeys (formerly " prosimians assigned"). They are nocturnal, tree-dwelling animals living in Africa and Asia that have developed a slow mode of locomotion that is unique among primates. The family is divided into nine to eleven types, depending on the author.

features

Loris are relatively small primates. They reach a head body length of 18 to 40 centimeters, the tail is only a short stub. The weight varies between 0.1 and 2 kilograms. Their short fur is dense and woolly, it is usually gray or brown in color and a little lighter on the underside.

A motto : When the hand is held towards the camera, the strong thumb and the receding second finger are easily recognizable.

The front and rear legs are approximately the same length. The thumb and the first toe are each strongly developed and the other rays can be opposed , the second finger and the second toe, however, are greatly reduced in size. The thumb or the big toe, together with the third to fifth rays of the hands and feet, form powerful "grasping pliers" that enable a strong grip on a branch. A special capillary network (" rete mirabile ") in the hands ensures the blood supply to the fingers and toes even during hours of clasps. All fingers and toes have nails with the exception of the second toe, which has the cleaning claw common for wet-nosed monkeys .

In connection with the climbing lifestyle, there are also modifications to the spine . The number of thoracic vertebrae is increased (15 or 16 compared to 12 or 13 in the other wet-nosed monkeys), which ensures greater mobility and enables an almost snake-like twisting around the branches. The number of sacral vertebrae is also increased (usually 6 or 7 compared to 3 in the other wet-nosed monkeys), which presumably ensures greater stability in the horizontal climbing posture. The number of caudal vertebrae, however , at 7 to 11, is significantly lower than that of most other wet-nosed monkeys (23 to 26). The regression of the tail is probably related to the fact that her climbing technique does not require a balance organ.

2 · 1 · 3 · 3  =  36
2 · 1 · 3 · 3
Loris tooth formula

The head of the Loris is characterized by the large eyes, which is an adaptation to the nocturnal way of life. The eyes are rounded, directed forward and opened slightly upwards. The ears are round, but significantly smaller than those of the closely related Galagos and are partly hidden in the fur. The tooth formula is I 2- C 1- P 3- M 3, so you have a total of 36 teeth. As with most wet-nosed monkeys, the lower incisors and canines form a forward-facing tooth comb .

At least the slow loris is known to be one of the few poisonous mammals. A gland on the arm produces a secretion that, in conjunction with saliva, develops its toxicity. They lick themselves off, the poison drives away a number of potential predators, but it can also be transmitted with bites.

distribution and habitat

Loris live in central Africa as well as in South and Southeast Asia . In Africa, its range extends over a wide strip from Guinea to the Republic of Congo and western Kenya . In Asia, their distribution area is divided into two parts: on the one hand, they are native to southern India and Sri Lanka , on the other hand, they come from northeastern India over the Malay Peninsula to Borneo and Java . Their habitat are tropical rainforests and other forest forms, whereby they always stay in densely leafy habitats.

Way of life

Activity times and movement

Loris are nocturnal tree dwellers that hardly ever get to the ground. During the day they sleep wrapped around a branch or hidden in the thick foliage - they do not build nests. At night they go in search of food. They have developed a mode of locomotion that is unique for primates: they are slow "grasping tong climbers". They usually hold on to at least three of the four limbs and put one hand or foot forward. Their firm grip can hardly be loosened even with force; in the event of a threat they cling tightly to the branch and can, if necessary, remain in this position for hours.

Thanks to their flexible spine, they can twist around branches well. They have lost the ability to jump, gaps in the branches are overcome with the "boom technique". They hold on with their hind legs and stretch their bodies horizontally forwards so that they can grab a new branch with their hands. The great effort required in this position could be a reason for the increase in the number of sacral vertebrae.

Social behavior

Due to their hidden, shy way of life, relatively little is known about the social behavior of the Loris. When foraging for food, they are usually out and about individually, and sleeping places are often sought out alone - only the slim loris sometimes sleep in small groups. They are territorial animals, they urinate on their hands and leave behind a scent trail on their forays that draws their conspecifics attention to their presence.

Males usually react aggressively to other males and drive them out of their territory, but their territory can overlap with that of several females.

Loris are noticeably quiet animals, they move noiselessly and do not give back loud vocalizations for communication with conspecifics.

food

Loris are omnivores that mainly eat fruits, insects and tree sap; to a lesser extent, they also eat other small animals, small vertebrates, eggs and various parts of plants. The composition of the food can vary depending on the species and habitat. When hunting, they cautiously sneak up on their prey and then grab hold of both front paws with a lightning-fast movement.

Reproduction

The males breed with all females whose territory overlaps with theirs. After a gestation period of around 130 to 190 days, the female usually gives birth to a single young. This clings to the mother in the first days of life, but is later left on a branch during her nocturnal foraging for food. They are weaned after three to nine months and are sexually mature at eight to 24 months. The life expectancy of the Loris in human care can be over 25 years.

Danger

The main threats to the Loris include the destruction of their habitat and hunting. The slow loris in particular , with which there are some superstitious beliefs and which are also kept as pets , are affected by hunting.

Systematics

External system

The closest relatives of the Loris are the Galagos , which are sometimes classified as a subfamily of the Loris. In contrast to the Loris, the Galagos are noisy and fast climbers or jumpers. Loris and Galagos together form the Lori-like (Lorisiformes), which are classified as wet-nosed monkeys together with the lemurs .

Internal system

The exact number of species of Loris is controversial. Today the following genera and species are distinguished

The African loris (bear lemurs and potto, subfamily Perodictinae) and the Asian loris (slender and slow loris, subfamily Lorisinae) are sister groups . The position of the controversial Wrong Potto is unclear.

literature

Individual evidence

  1. ↑ Geissmann (2003), p. 78
  2. ↑ after Mittermeier & Rylands & Wilson (2013)
  3. ↑ Rachel A. Munds, Chelsea L. Titus, Lori S. Eggert, Gregory E. Blomquist: Using a multi-gene approach to infer the complicated phylogeny and evolutionary history of lorises (Order Primates: Family Lorisidae). Molecular Phylogenetics and Evolution, May 2018, doi: 10.1016 / j.ympev.2018.05.025

Web links

Commons : Loris (Loridae)  - Collection of images, videos and audio files