The group size is individuals. Each group has a territory of hectares, which is aggressively defended from other groups. Gibbon pair-bonds last for many years.
Locomotion Gibbons move mainly by swinging by their arms brachiation , but they can also walk on two legs bipedalism. The spectacular brachiation of the gibbons makes them the most acrobatic of all apes. When in a hurry, gibbons seem to be virtually flying through the treetops. On branches and the ground, gibbons walk on two legs.
Therefore, gibbons are possibly the best primate model for the evolution of bipedalism in humans. Anatomy Gibbons exhibit numerous anatomical specialisations which are linked to their unusual locomotion. For instance, their arms are particularly elongated.
Relative to body size, gibbons have the longest arms of all primates. Gibbons weigh only kg there is variation between the species and are therefore the smallest of the apes. Their light build makes enables them to collect fruit from thin branches. Like the other apes, gibbons do not have a tail. Click here to see a short video clip of wild gibbons moving around in the tree crowns Hylobates muelleri video: Yoichi Inoue.
Systematics There are four main groups of gibbons. These are thought to represent different genera, which are as distant to each other as humans and chimpanzees.
Siamangs Symphalangus 1 species Crested gibbons Nomascus 4 species Hoolocks Hoolock 1 species Lar or dwarf gibbons Hylobates 6 species Distribution Gibbons have a large range that extends over almost all of Southeast Asia. Gibbons are distributed over most of Indo-Burma and Sundaland. These are two of earth's biologically richest and most endangered terrestrial ecoregions. Gibbon songs Early in the morning, gibbons produce spectacular songs, which can be heard as far as km away.
Singing is very rare in mammals. Gibbons produce the most complex songs of all land mammals. They move swiftly through the trees in a motion called brachiation , meaning they swing from branch to branch. One strong hand grasps a branch, and the other long arm stretches out to a reach faraway branch. They cross gaps as wide as 15 metres in a single swinging move. The long, powerful legs help propel them as they swing. Their shoulder joints are specially adapted to allow a greater range of motion when swinging.
They can travel this way as fast as 56 kilometres an hour, looking as though they are flying. When gibbons do walk, either along branches or the very rare times they come to the ground, they walk on two legs, throwing their long arms above their head for balance.
Walking on two legs is called bipedalism. Gibbons do not walk on all four legs. Gibbons live in family groups of , consisting of an adult pair and their young. They defend territory aggressively. Unlike other apes, gibbons do not make nests to sleep in, but sleep upright on tree branches. They have specially tough pads on their bottoms so they can sit comfortably. Gibbons make loud calls that echo for miles through the forest. Some species have large throat pouches so that their calls are echoed further.
In the early morning, the rainforest echoes with gibbon songs. Mated pairs sing duets but sometimes the family sings together. Gibbon songs last for between 10 and 30 minutes, and identify each animal. The songs probably also help to mark boundaries and to find partners. Gibbons pair for life, which is rare among primates. The adult female is the dominant one in the group, the next most powerful are her daughters, then her sons, and then her male mate. As fruit trees are plentiful in their habitat, fruit forms the main part of a gibbon diet, and they are especially fond of figs.
They also occasionally eat leaves and insects. Their brachiating ability gives gibbons the advantage of being able to swing out and grab fruits growing at the end of branches, an advantage over other animals with a similar diet.
About 7 months after mating with a male, a female gibbon gives birth to a single young. Females give birth every years, and the young stay with their parents for years before moving away. Whereas humans and horses have two very distinct gaits, walking and running, gibbons only rarely engage in a way of locomotion that resembles our walk, where the legs are swung like pendulums.
Instead, at all speeds, they propel themselves in a springy, bouncy fashion closer to our run. But unlike humans, they do not use their Achilles tendons as the main spring. Vereecke hypothesizes that they might use their quadriceps muscles instead.
Also unlike a human, they never have both feet off the ground at the same time. Vereecke suggests that this 'aerial phase' think of this lovely expression on your next jog should not be a requirement to call something a run. Vereecke says that the apes are good at bipedalism, even though the animals are much more often found swinging from limb to limb.
She wonders whether there is some fundamental aspect of physiology that might make swinging animals adaptable to walking.
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