Rectilinear locomotion or rectilinear progression is a mode of locomotion most often associated with

snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...

s. In particular, it is associated with heavy-bodied species such as terrestrial African adders, pythons and boas; however, most snakes are capable of it. It is one of at least five forms of locomotion used by snakes, the others being lateral undulation,

sidewinding Sidewinding is a type of locomotion unique to snakes, used to move across loose or slippery substrates. It is most often used by the Saharan horned viper, '' Cerastes cerastes'', the Mojave sidewinder rattlesnake, '' Crotalus cerastes'', and th ...

, concertina movement, and slide-pushing. Unlike all other modes of snake locomotion, which include the snake bending its body, the snake flexes its body only when turning in rectilinear locomotion.

Biomechanics of rectilinear locomotion

Rectilinear locomotion relies upon two opposing

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

s, the costocutaneous inferior and superior, which are present on every

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

and connect the ribs to the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

. Although it was originally believed that the ribs moved in a "walking" pattern during rectilinear movement, studies have shown that the ribs themselves do not move; only the muscles and the skin move to produce forward motion. First, the costocutaneous superior lifts a section of the snake's belly from the ground and places it ahead of its former position. Then the costocutaneous inferior pulls backwards while the belly scales are on the ground, propelling the snake forwards. These sections of contact propagate posteriorly, which results in the ventral surface, or belly, moving in discrete sections akin to "steps" while the overall body of the snake moves continuously forward at a relatively constant speed.

Uses of rectilinear locomotion

This method of locomotion is extremely slow (between ), but is also almost noiseless and very hard to detect, making it the mode of choice for many species when stalking prey. It is primarily used when the space being traversed is too constricting to allow for other forms of movement. When climbing, snakes will often use rectilinear locomotion in conjunction with concertina movements to exploit terrain features such as interstices in the surfaces they are climbing. Rectilinear locomotion may also be useful after snakes eat. Snakes have more difficulty bending their spines after consuming large prey, and rectilinear movement requires less flexing of the spine than other locomotion types.

In robotics

The development of rectilinear movement in

robotics Robotics is the interdisciplinary study and practice of the design, construction, operation, and use of robots. Within mechanical engineering, robotics is the design and construction of the physical structures of robots, while in computer s ...

is centered around the development of snakelike

robot A robot is a machine—especially one Computer program, programmable by a computer—capable of carrying out a complex series of actions Automation, automatically. A robot can be guided by an external control device, or the robot control, co ...

s, which have significant advantages over robots with wheeled or bipedal locomotion. The primary advantage in the creation of a serpentine robot is that the robot is often capable of traversing rough, muddy, and complex terrain that is often prohibitive to wheeled

robots" \n\n\n\n\n\n\nrobots.txt is the filename used for implementing the Robots Exclusion Protocol, a standard used by websites to indicate to visiting web crawlers and other web robots which portions of the website they are allowed to visit.\n\nThe sta ...

. Secondly, due to the mechanisms responsible for rectilinear and other forms of serpentine locomotion, the robots tend to have repetitive motor elements, which makes the entire robot relatively robust to mechanical failure.

References

{{locomotion Snakes Terrestrial locomotion

Biomechanics of rectilinear locomotion

Uses of rectilinear locomotion

In robotics

See also

References