Arboreal locomotion

Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose numerous mechanical challenges to animals moving through them and lead to a variety of anatomical, behavioral and ecological consequences as well as variations throughout different species.[1] Furthermore, many of these same principles may be applied to climbing without trees, such as on rock piles or mountains.

The earliest known tetrapod with specializations that adapted it for climbing trees was Suminia, a synapsid of the Late Permian, about 260 million years ago.[2]

Some animals are exclusively arboreal in habitat, such as the tree snail.

Leopard on the tree
Leopards are good climbers and can carry their kills up their trees to keep them out of reach from scavengers and other predators.

Biomechanics

Arboreal habitats pose numerous mechanical challenges to animals moving in them, which have been solved in diverse ways. These challenges include moving on narrow branches, moving up and down inclines, balancing, crossing gaps, and dealing with obstructions.[1]

Diameter

Moving along a narrow surface poses special difficulties to animals. During locomotion on the ground, the location of the center of mass may swing from side to side, but during arboreal locomotion, this would result in the center of mass moving beyond the edge of the branch, resulting in a tendency to topple over. Additionally, foot placement is constrained by the need to make contact with the narrow branch. This narrowness severely restricts the range of movements and postures an animal can use to move.

Incline

Branches are frequently oriented at an angle to gravity in arboreal habitats, including being vertical, which poses special problems. As an animal moves up an inclined branch, they must fight the force of gravity to raise their body, making the movement more difficult. Conversely, as the animal descends, it must also fight gravity to control its descent and prevent falling. Descent can be particularly problematic for many animals, and highly arboreal species often have specialized methods for controlling their descent.

Balance

Due to the height of many branches and the potentially disastrous consequences of a fall, balance is of primary importance to arboreal animals.[1] On horizontal and gently sloped branches, the primary problem is tipping to the side due to the narrow base of support.[1] The narrower the branch, the greater the difficulty in balancing a given animal faces. On steep and vertical branches, tipping becomes less of an issue, and pitching backwards or slipping downwards becomes the most likely failure.[1] In this case, large-diameter branches pose a greater challenge since the animal cannot place its forelimbs closer to the center of the branch than its hindlimbs.

Brachiating Gibbon (Some rights reserved)
Gibbons are very good brachiators because their elongated limbs enable them to easily swing and grasp on to branches.

Crossing gaps

Branches are not continuous, and any arboreal animal must be able to move between gaps in the branches, or even between trees. This can be accomplished by reaching across gaps, by leaping across them or gliding between them.

Obstructions

Arboreal habitats often contain many obstructions, both in the form of branches emerging from the one being moved on and other branches impinging on the space the animal needs to move through. These obstructions may impede locomotion, or may be used as additional contact points to enhance it. While obstructions tend to impede limbed animals,[3][4] they benefit snakes by providing anchor points.[5][6][7]

Anatomical specializations

Arboreal organisms display many specializations for dealing with the mechanical challenges of moving through their habitats.[1]

Limb length

Arboreal animals frequently have elongated limbs that help them cross gaps, reach fruit or other resources, test the firmness of support ahead, and in some cases, to brachiate.[1] However, some species of lizard have reduced limb size that helps them avoid limb movement being obstructed by impinging branches.

Prehensile tails

Many arboreal species, such as tree porcupines, green tree pythons, emerald tree boas, chameleons, silky anteaters, spider monkeys, and possums, use prehensile tails to grasp branches. In the spider monkey and crested gecko, the tip of the tail has either a bare patch or adhesive pad, which provide increased friction.

Claws

Claws can be used to interact with rough substrates and re-orient the direction of forces the animal applies. This is what allows squirrels to climb tree trunks that are so large as to be essentially flat, from the perspective of such a small animal. However, claws can interfere with an animal's ability to grasp very small branches, as they may wrap too far around and prick the animal's own paw.

Two-toed anteater balanced on a stick
The silky anteater uses its prehensile tail as a third arm for stabilization and balance, while its claws help better grasp and climb onto branches.

Adhesion

Adhesion is an alternative to claws, which works best on smooth surfaces. Wet adhesion is common in tree frogs and arboreal salamanders, and functions either by suction or by capillary adhesion. Dry adhesion is best typified by the specialized toes of geckos, which use van der Waals forces to adhere to many substrates, even glass.

Gripping

Frictional gripping is used by primates, relying upon hairless fingertips. Squeezing the branch between the fingertips generates a frictional force that holds the animal's hand to the branch. However, this type of grip depends upon the angle of the frictional force, thus upon the diameter of the branch, with larger branches resulting in reduced gripping ability. Animals other than primates that use gripping in climbing include the chameleon, which has mitten-like grasping feet, and many birds that grip branches in perching or moving about.

Reversible feet

To control descent, especially down large diameter branches, some arboreal animals such as squirrels have evolved highly mobile ankle joints that permit rotating the foot into a 'reversed' posture. This allows the claws to hook into the rough surface of the bark, opposing the force of gravity.

Low center of mass

Many arboreal species lower their center of mass to reduce pitching and toppling movement when climbing. This may be accomplished by postural changes, altered body proportions, or smaller size.

Small size

Small size provides many advantages to arboreal species: such as increasing the relative size of branches to the animal, lower center of mass, increased stability, lower mass (allowing movement on smaller branches), and the ability to move through more cluttered habitat.[1] Size relating to weight affects gliding animals such as the reduced weight per snout-vent length for 'flying' frogs.[8]

Hanging under perches

Some species of primate, bat, and all species of sloth achieve passive stability by hanging beneath the branch.[1] Both pitching and tipping become irrelevant, as the only method of failure would be losing their grip.

Gecko
The gecko's toes adhere to surfaces via dry adhesion, to allow them to stay firmly attached to a branch or even a flat wall.

Behavioral specializations

Arboreal species have behaviors specialized for moving in their habitats, most prominently in terms of posture and gait. Specifically, arboreal mammals take longer steps, extend their limbs further forwards and backwards during a step, adopt a more 'crouched' posture to lower their center of mass, and use a diagonal sequence gait.

Ecological consequences

Arboreal locomotion allows animals access to different resources, depending upon their abilities. Larger species may be restricted to larger-diameter branches that can support their weight, while smaller species may avoid competition by moving in the narrower branches.

Climbing without trees

Many animals climb in other habitats, such as in rock piles or mountains, and in those habitats, many of the same principles apply due to inclines, narrow ledges, and balance issues. However, less research has been conducted on the specific demands of locomotion in these habitats.

Perhaps the most exceptional of the animals that move on steep or even near vertical rock faces by careful balancing and leaping are the various types of mountain dwelling caprid such as the Barbary sheep, markhor, yak, ibex, tahr, rocky mountain goat, and chamois. Their adaptations may include a soft rubbery pad between their hooves for grip, hooves with sharp keratin rims for lodging in small footholds, and prominent dew claws. The snow leopard, being a predator of such mountain caprids, also has spectacular balance and leaping abilities; being able to leap up to ≈17m (~50 ft). Other balancers and leapers include the mountain zebra, mountain tapir, and hyraxes.

Brachiation


Brachiation is a specialized form of arboreal locomotion, used by primates to move very rapidly while hanging beneath branches. Arguably the epitome of arboreal locomotion, it involves swinging with the arms from one handhold to another. Only a few species are brachiators, and all of these are primates; it is a major means of locomotion among spider monkeys and gibbons, and is occasionally used by the female orangutans. Gibbons are the experts of this mode of locomotion, swinging from branch to branch distances of up to 15 m (50 ft), and traveling at speeds of as much as 56 km/h (35 mph).

Gliding and parachuting

To bridge gaps between trees, many animals such as the flying squirrel have adapted membranes, such as patagia for gliding flight. Some animals can slow their descent in the air using a method known as parachuting, such as Rhacophorus (a "flying frog" species) that has adapted toe membranes allowing it to fall more slowly after leaping from trees.[9]

Limbless climbing

Many species of snake are highly arboreal, and some have evolved specialized musculature for this habitat.[10] While moving in arboreal habitats, snakes move slowly along bare branches using a specialized form of concertina locomotion,[11] but when secondary branches emerge from the branch being moved on, snakes use lateral undulation, a much faster mode.[12] As a result, snakes perform best on small perches in cluttered environments, while limbed organisms seem to do best on large perches in uncluttered environments.[12]

Arboreal animals

Cepaea nemoralis active pair on tree trunk
Arboreal snails use their sticky slime to help in climbing up trees since they lack limbs to do so.

Many species of animals are arboreal, far too many to list individually. This list is of prominently or predominantly arboreal species and higher taxa.

See also

  • Tree template.svg Trees portal

References

  1. ^ a b c d e f g h i Cartmill, M. (1985). Climbing. In Functional Vertebrate Morphology, eds. M. Hildebrand D. M. Bramble K. F. Liem and D. B. Wake, pp. 73–88. Cambridge: Belknap Press.
  2. ^ Fröbisch, Jörg; Reisz, Robert R. (2009). "The Late Permian herbivore Suminia and the early evolution of arboreality in terrestrial vertebrate ecosystems". Proceedings of the Royal Society B. 276 (1673): 3611–3618. doi:10.1098/rspb.2009.0911. PMC 2817304. PMID 19640883.
  3. ^ Jones, Zachary M.; Jayne, Bruce C. (2012-06-15). "Perch diameter and branching patterns have interactive effects on the locomotion and path choice of anole lizards". Journal of Experimental Biology. 215 (12): 2096–2107. doi:10.1242/jeb.067413. ISSN 0022-0949. PMID 22623198.
  4. ^ Hyams, Sara E.; Jayne, Bruce C.; Cameron, Guy N. (2012-11-01). "Arboreal Habitat Structure Affects Locomotor Speed and Perch Choice of White-Footed Mice (Peromyscus leucopus)". Journal of Experimental Zoology Part A: Ecological Genetics and Physiology. 317 (9): 540–551. doi:10.1002/jez.1746. ISSN 1932-5231. PMID 22927206.
  5. ^ Jayne, Bruce C.; Herrmann, Michael P. (July 2011). "Perch size and structure have species-dependent effects on the arboreal locomotion of rat snakes and boa constrictors". Journal of Experimental Biology. 214 (13): 2189–2201. doi:10.1242/jeb.055293. ISSN 0022-0949. PMID 21653813.
  6. ^ Astley, Henry C.; Jayne, Bruce C. (March 2009). "Arboreal habitat structure affects the performance and modes of locomotion of corn snakes (Elaphe guttata)". Journal of Experimental Zoology Part A: Ecological Genetics and Physiology. 311A (3): 207–216. doi:10.1002/jez.521. ISSN 1932-5231. PMID 19189381.
  7. ^ Mansfield, Rachel H.; Jayne, Bruce C. (2011). "Arboreal habitat structure affects route choice by rat snakes". Journal of Comparative Physiology A. 197 (1): 119–129. doi:10.1007/s00359-010-0593-6. PMID 20957373.
  8. ^ Emerson, S.B.; Koehl, M.A.R. (1990). "The interaction of behavioral and morphological change in the evolution of a novel locomotor type: 'Flying' frogs". Evolution. 44 (8): 1931–1946. doi:10.2307/2409604. JSTOR 2409604.
  9. ^ John R. Hutchinson. "Gliding and Parachuting". www.ucmp.berkeley.edu. Regents of the University of California.
  10. ^ "Jayne, B.C. (1982). Comparative morphology of the semispinalis-spinalis muscle of snakes and correlations with locomotion and constriction. J. Morph, 172, 83-96" (PDF). Retrieved 2013-08-15.
  11. ^ Astley, H. C. and Jayne, B. C. (2007). Effects of perch diameter and incline on the kinematics, performance, and modes of arboreal locomotion of corn snakes (Elaphe guttata)" J. Exp. Biol. 210, 3862-3872. Archived June 17, 2010, at the Wayback Machine
  12. ^ a b "Astley, H. C. a. J., B.C. (2009). Arboreal habitat structure affects the performance and modes of locomotion of corn snakes (Elaphe guttata). Journal of Experimental Zoology Part A: Ecological Genetics and Physiology 311A, 207-216" (PDF). Retrieved 2013-08-15.

Sources

Animal locomotion

Animal locomotion, in ethology, is any of a variety of methods that animals use to move from one place to another. Some modes of locomotion are (initially) self-propelled, e.g., running, swimming, jumping, flying, hopping, soaring and gliding. There are also many animal species that depend on their environment for transportation, a type of mobility called passive locomotion, e.g., sailing (some jellyfish), kiting (spiders), rolling (some beetles and spiders) or riding other animals (phoresis).

Animals move for a variety of reasons, such as to find food, a mate, a suitable microhabitat, or to escape predators. For many animals, the ability to move is essential for survival and, as a result, natural selection has shaped the locomotion methods and mechanisms used by moving organisms. For example, migratory animals that travel vast distances (such as the Arctic tern) typically have a locomotion mechanism that costs very little energy per unit distance, whereas non-migratory animals that must frequently move quickly to escape predators are likely to have energetically costly, but very fast, locomotion.

The anatomical structures that animals use for movement, including cilia, legs, wings, arms, fins, or tails are sometimes referred to as locomotory organs or locomotory structures.

Archaeolemur

Archaeolemur is an extinct genus of lemurs that includes two species, Archaeolemur edwardsi and A. majori.The genus was widespread throughout Madagascar through much of the Holocene epoch, and its remains are often abundant at fossil sites across the island. Jungers estimated their body weight to be between 15 and 35 kg. The wide geographical and temporal range of the genus may be attributed its generalist nature. Archaeolemur was a semiterrestrial quadruped that spent much of its time on the ground, although it was also well suited to arboreal locomotion. Despite its tendency for a mostly terrestrial lifestyle, it was not as well suited for cursorial locomotion as macaques or baboons, the extant primates the genus is often compared to. When compared to highly terrestrial baboons, Archaeolemur had shorter, more robust limbs, smaller digits, and a wider trunk. Its diet is thought to have encompassed a wide range of foods including seeds and savanna plants. The incisors of Archaeolemur were enlarged and adapted to remove hard shells and rinds from seeds and fruit. The eurytopic adaptation of Archaeolemur may explain why it was one of the last of the subfossil lemurs to have gone extinct. It disappeared from Madagascar around 1047–1280 CE.

Basal (phylogenetics)

In phylogenetics, basal is the direction of the base (or root) of a rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to the root. Each node in the tree corresponds to a clade; i.e., clade C may be described as basal within a larger clade D if its root is directly linked to the root of D. The terms deep-branching or early-branching are similar in meaning.

While there must always be two or more equally basal clades sprouting from the root of every cladogram, those clades may differ widely in taxonomic rank and/or species diversity. If C is a basal clade within D that has the lowest rank of all basal clades within D, C may be described as the basal taxon of that rank within D. Greater diversification may be associated with more evolutionary innovation, but ancestral characters should not be imputed to the members of a less species-rich basal clade without additional evidence, as there can be no assurance such an assumption is valid.In general, clade A is more basal than clade B if B is a subgroup of the sister group of A. Within large groups, "basal" may be used loosely to mean 'closer to the root than the great majority of', and in this context terminology such as "very basal" may arise. A 'core clade' is a clade representing all but the basal clade(s) of lowest rank within a larger clade; e.g., core eudicots.

Brachiation

Brachiation (from "brachium", Latin for "arm"), or arm swinging, is a form of arboreal locomotion in which primates swing from tree limb to tree limb using only their arms. During brachiation, the body is alternately supported under each forelimb. This form of locomotion is the primary means of locomotion for the small gibbons and siamangs of southeast Asia. Gibbons in particular use brachiation for as much as 80% of their locomotor activities. Some New World monkeys, such as spider monkeys and muriquis, were initially classified as semibrachiators and move through the trees with a combination of leaping and brachiation. Some New World species also practice suspensory behaviors by using their prehensile tail, which acts as a fifth grasping hand. Evidence has shown that the extinct ape Proconsul from the Milocene of East Africa developed an early form of suspensory behaviour, and was therefore referred to as a probrachiator.Upon further observations and more in depth understandings of the anatomy and behaviour of primates, the terms semibrachiator and probrachiator have largely fallen out of favour within the scientific community. Currently, researchers classify gibbons and siamangs as the only true brachiators and classify the great apes as modified brachiators. All other brachiation behaviours that do not meet either of these classifications are referred to as forearm suspensory postures and locomotion.Some traits that allow primates to brachiate include a short spine (particularity the lumbar spine), short fingernails (instead of claws), long curved fingers, reduced thumbs, long forelimbs and freely rotating wrists. Modern humans retain many physical characteristics that suggest a brachiator ancestor, including flexible shoulder joints and fingers well-suited for grasping. In lesser apes, these characteristics were adaptations for brachiation. Although great apes do not normally brachiate (with the exception of orangutans), our human anatomy suggests that brachiation may be an exaptation to bipedalism, and healthy modern humans are still capable of brachiating. Some children's parks include monkey bars which children play on by brachiating.

As well as shaping the evolution of gibbon body structure, brachiation has influenced the style and order of their behaviour. For example, unlike other primates who carry infants on their back, gibbons will carry young ventrally. It also affects their play activities, copulation, and fighting. It is thought that gibbons gain evolutionary advantages through brachiation and being suspended by both hands (bimanual suspension) when feeding. While smaller primates cannot hold themselves by both hands for long periods, and larger primates are too heavy to exploit food resources on the ends of branches, gibbons can remain suspended for a significant period and use their long arms to reach food in terminal branches more easily. Another theory postulates that brachiation is a quieter and less obvious mode of locomotion than quadrupedal jumping and climbing thereby more successfully avoiding predators.

Climbing (disambiguation)

Climbing is the human activity of ascending a steep object with the hands and/or feet.

Climbing, Climb or The climb may also refer to:

Climbing (sport)

Climbing (magazine)

Arboreal locomotion, animal locomotion while on trees. Also includes locomotion on mountains/cliffs/rocks.

Climbing specialist, a racing cyclist who is especially competitive on hills

Climb (aeronautics), an aviation term

Climb (dislocation), see Dislocation

Climb (plants), see Vine

"Climbing", an episode of the television series Zoboomafoo

Concertina movement

Concertina movement is the movement occurring in snakes and other legless organisms that consists of gripping or anchoring with portions of the body while pulling or pushing other sections in the direction of movement.

Dalinghosaurus

Dalinghosaurus (often incorrectly spelled "Dalinghesaurus") is an extinct genus of lizards, first described in 1998 by S.A. Ji of the Peking University Department of Geology. The type species is Dalinghosaurus longidigitus.

Force platform

Force platforms or force plates are measuring instruments that measure the ground reaction forces generated by a body standing on or moving across them, to quantify balance, gait and other parameters of biomechanics. Most common areas of application are medicine and sports.

Gait

Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency. Different animal species may use different gaits due to differences in anatomy that prevent use of certain gaits, or simply due to evolved innate preferences as a result of habitat differences. While various gaits are given specific names, the complexity of biological systems and interacting with the environment make these distinctions 'fuzzy' at best. Gaits are typically classified according to footfall patterns, but recent studies often prefer definitions based on mechanics. The term typically does not refer to limb-based propulsion through fluid mediums such as water or air, but rather to propulsion across a solid substrate by generating reactive forces against it (which can apply to walking while underwater as well as on land).

Due to the rapidity of animal movement, simple direct observation is rarely sufficient to give any insight into the pattern of limb movement. In spite of early attempts to classify gaits based on footprints or the sound of footfalls, it was not until Eadweard Muybridge and Étienne-Jules Marey began taking rapid series of photographs that proper scientific examination of gaits could begin.

Primate

A primate ( (listen) PRY-mayt) (from Latin primat-, from primus: "prime, first rank") is a eutherian mammal constituting the taxonomic order Primates. Primates arose 85–55 million years ago from small terrestrial mammals (Primatomorpha), which adapted to living in the trees of tropical forests: many primate characteristics represent adaptations to life in this challenging environment, including large brains, visual acuity, color vision, altered shoulder girdle, and dexterous hands. Primates range in size from Madame Berthe's mouse lemur, which weighs 30 g (1 oz), to the eastern gorilla, weighing over 200 kg (440 lb). There are 190–448 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the first decade of the 2000s, and eleven since 2010.

Primates are divided into two distinct suborders (see diagram under History of terminology). The first is the strepsirrhines (from Greek 'wet-nosed') – lemurs, galagos, and lorisids. (The colloquial names ending in -nosed actually refer to the rhinarium of the primate.) The second is haplorhines - the "dry-nosed" primates (from Greek 'simple-nosed') - tarsier, monkey, and ape clades, the last of these including humans. Simians (infraorder Simiiformes, from Greek simos 'flat-nosed') are monkeys and apes, cladistically including: the catarrhines (from Latin 'narrow nosed') consisting of the Old World monkeys and apes; and the platyrrhines (from Latin 'flat-nosed'): this division occurred about 60 million years ago. Forty million years ago, simians from Africa migrated to South America, presumably by drifting on debris, and gave rise to the New World monkeys. Twenty five million years ago the remaining Old World simians (catarrhines) split into apes and Old World monkeys. Common names for the simians are the (Old World) baboons, macaques, gibbons, and great apes; and the (New World) capuchins, howlers and squirrel monkeys.

Primates have large brains (relative to body size) compared to other mammals, as well as an increased reliance on visual acuity at the expense of the sense of smell, which is the dominant sensory system in most mammals. These features are more developed in monkeys and apes, and noticeably less so in lorises and lemurs. Some primates are trichromats, with three independent channels for conveying color information. Except for apes, primates have tails. Most primates also have opposable thumbs. Many species are sexually dimorphic; differences may include muscle mass, fat distribution, pelvic width, canine tooth size, hair distribution, and coloration. Primates have slower rates of development than other similarly sized mammals, reach maturity later, and have longer lifespans. Depending on the species, adults may live in solitude, in mated pairs, or in groups of up to hundreds of members. Some primates, including gorillas, humans and baboons, are primarily terrestrial rather than arboreal, but all species have adaptations for climbing trees. Arboreal locomotion techniques used include leaping from tree to tree and swinging between branches of trees (brachiation); terrestrial locomotion techniques include walking on two limbs (bipedalism) and modified walking on four limbs (knuckle-walking).

Primates are among the most social of animals, forming pairs or family groups, uni-male harems, and multi-male/multi-female groups. Non-human primates have at four types of social systems, many defined by the amount of movement by adolescent females between groups. Most primate species remain at least partly arboreal: the exceptions are some great apes, baboons, and humans, who left the trees for the ground and now inhabit every continent.

Close interactions between humans and non-human primates (NHPs) can create opportunities for the transmission of zoonotic diseases, especially virus diseases, including herpes, measles, ebola, rabies, and hepatitis. Thousands of non-human primates are used in research around the world because of their psychological and physiological similarity to humans. About 60% of primate species are threatened with extinction. Common threats include deforestation, forest fragmentation, monkey drives, and primate hunting for use in medicines, as pets, and for food. Large-scale tropical forest clearing for agriculture most threatens primates.

Quokka

The quokka (), Setonix brachyurus, the only member of the genus Setonix, is a small macropod about the size of a domestic cat. Like other marsupials in the macropod family (such as kangaroos and wallabies), the quokka is herbivorous and mainly nocturnal.Quokkas are found on some smaller islands off the coast of Western Australia, particularly Rottnest Island, just off Perth, and also Bald Island near Albany, and in isolated scattered populations in forest and coastal heath between Perth and Albany. A small colony exists at the eastern limit of their range in a protected area of Two Peoples Bay Nature Reserve, where they co-exist with the critically endangered Gilbert's potoroo.

Rhacophorus

Rhacophorus is a genus of frogs in the shrub frog family (Rhacophoridae) which together with the related Hylidae makes up the true tree frogs. They live in India, Japan, Madagascar, Africa, and Southeast Asia. "Amphibian Species of the World 5.6" lists 81 species.These frogs have long toes with strong webbing between them, enabling the animals to slow their fall to a glide, a form of arboreal locomotion known as 'parachuting'. They are therefore among the anurans commonly known as "flying frogs".

The present genus is closely related to Polypedates, which in former times was often included in Rhacophorus. Even today, it is not fully resolved in which of these genera "P." feae and the Chinese flying frog ("R." dennysi) properly belong, and the supposedly new species "P. pingbianensis" has turned out to be the same as R. duboisi.

Sesamoid bone

In anatomy, a sesamoid bone () is a bone embedded within a tendon or a muscle. It is derived from the Latin word sesamum ("sesame seed"), due to the small size of most sesamoids. Often, these bones form in response to strain, or can be present as a normal variant. The kneecap is the largest sesamoid bone in the body. Sesamoids act like pulleys, providing a smooth surface for tendons to slide over, increasing the tendon's ability to transmit muscular forces.The sesamoid is a small nodular bone most often present embedded in tendons in the region of the thumb. Calcification of sesamoid bone is one of the important features of pubertal growth spurt, which is earlier in females than in males. Absence of sesamoid bone indicates delay in reaching puberty.

Slender loris

Slender lorises (Loris) are a genus of loris native to India and Sri Lanka.The slender loris spends most of its life in trees (arboreal), traveling along the top of branches with slow and precise movements .It is found in tropical rainforests, scrub forest, semi deciduous forest and swamps. The species have lifespans of 15 years and are nocturnal. Slender lorises generally feed on insects, reptiles, shoots of plants and fruits. Locally, they are known as Devanga Pilli ("దేవాంగ పిల్లి") in Telugu, kaadu paapa ("ಕಾಡು ಪಾಪ") in Kannada, kutti thevangu ("தேவாங்கு") in Tamil and Malayalam, and unahapuluwa ("උනහපුළුවා") in Sri Lanka, and "Lajwanti" (लाजवंती) in Marathi.

Suspensory behavior

Suspensory behaviour is a form of arboreal locomotion or a feeding behavior that involves hanging or suspension of the body below or among tree branches. This behavior enables faster travel while reducing path lengths to cover more ground when travelling, searching for food and avoiding predators. Different types of suspensory behaviour include brachiation, climbing, and bridging. These mechanisms allow larger species to distribute their weight among smaller branches rather than balancing above these weak supports. Primates and sloths are most commonly seen using these behaviours, however, other animals such as bats may be seen hanging below surfaces to obtain food or when resting.

Tree-kangaroo

Tree-kangaroos are marsupials of the genus Dendrolagus, adapted for arboreal locomotion. They inhabit the tropical rainforests of New Guinea, far northeastern Queensland, and some of the islands in the region. Most tree-kangaroos are considered threatened due to hunting and habitat destruction. They are the only true arboreal macropods.

Tree snail

Tree snail is a common name that is applied to various kinds of tropical air-breathing land snails, pulmonate gastropod mollusks that have shells, and that live in trees, in other words, are exclusively arboreal in habitat.

Some other species of air-breathing land snails may sometimes be found on tree trunks, or even in the foliage of trees, but this does not mean they live their whole lives in trees, and they are not considered to be tree snails.

Vertical clinging and leaping

Vertical clinging and leaping (VCL) is a type of arboreal locomotion seen most commonly among the strepsirrhine primates and haplorrhine tarsiers. The animal begins at rest with its torso upright and elbows fixed, with both hands clinging to a vertical support, such as the side of a tree or bamboo stalk. To move from one support to another, it pushes off from one vertical support with its hindlimbs, landing on another vertical support after an extended period of free flight. Vertical clinging and leaping primates have evolved a specialized anatomy to compensate for the physical implications of this form of locomotion. These key morphological specializations have been identified in prosimian fossils from as early as the Eocene.

Gait class
Anatomy
Specific

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