The method of locomotion familiar to kangaroos likely evolved from the circumferential gait that was retained by the small and primitive rat kangaroo. The hind limbs became increasingly larger than the forelimbs and the hind feet became longer, providing a very efficient means of speed. Motion hopping. At equivalent speed, and accounting for differences in weight, a jumping kangaroo uses less energy than a galloping dog or horse.
But this specialization is not without a cost – a The typical kangaroo is unable to walk. When it moves slowly, it raises the hind legs on a tripod consisting of the forelimbs and the tail pressed down to the ground, then both hind limbs swing forward and always together. A land kangaroo cannot move each leg independently while supporting the body, although it can perform alternating kicks when swimming.
Kangaroos, which have undergone a secondary shortening of the hind feet, can alternately move their hind legs when walking along a branch. In typical kangaroos, the tail is not very flexible but moves up and down to aid balance during movement jumping gait; It acts as a fifth limb to support the body when moving slowly. In more primitive rat animals, the tail is moderately palpable in the vertical plane, and is used to carry bundles of nesting material.
The ability to glide independently arose in three families of marsupials: Pseudocheiridae, PetauridaeAnd acroptidae. In each case, this involves a membrane of skin between the forelimbs and hind limbs, which, when the legs are extended, expands into an oblong, kite-like airfoil.
Jumping from a high treeThe glider can hover over very long distances, orient itself by varying the tension of the membrane on either side, balancing with the tail outstretched, and finally orienting the body vertically to land on another tree trunk with its four feet. No other gliding mammal has anything that can compare to the tail of the feather-tailed glider: each side bears a thin row of stiff, closely packed hairs, all of the same length, forming a structure very similar to that of a quill.
Although it seems that Most marsupials are able to swim When necessary, only linabuck can be considered truly watery. With alternate strokes of its webbed hind feet, this Mesoamerican species swims at the bottom of a pond or stream with its eyes closed, groping with its long, outstretched fingers for live prey, which it grabs in its mouth and goes ashore to eat it. The posterior opening sac of the female yanabok is closed by a strong sphincter muscle and sealed with water-repellent secretions when the animal is swimming.
The most extreme locomotion specialty of any marsupial is the small sausage-shaped marsupial mole. It is blind, lacks external ears, and has a horny shield over the snout and around the nostrils. The limbs are short, with very strong bones and powerful muscles, and the spade-like forefeet has huge triangular claws on the third and fourth toes, with smaller claws on the other toes.
The forelimbs are used to dig in the soil in front of the animal and pull it forward. The hind feet, which have four short claws unique among marsupials, a claw-like structure on the first toe, are used to kick sand back from the body. The marsupial mole does not tunnel but “swims” across the sand, usually at a depth of 10 to 20 cm (4 to 8 in), but sometimes descending to a meter (62 ft) or more.
The feather-tailed glider, honey possum and pygmy possum, of the genus Cercartetus, are very small marsupials that climb by grasping at the tips of their fingers and extended toes. With the exception of the second and third joined toes of the hind feet, the claws are reduced and nail-like, and are located above the tips of the toes. The pads on the fingers and toes of the feather-tailed glider are microscopically grooved, like those of geckos, allowing it to stick to a smooth surface such as a vertical sheet of glass and even anchor itself, albeit briefly, to the underside of a horizontal sheet.