science

Rectilinear locomotion

Rectilinear locomotion is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Rectilinear locomotion rather than just read about it. In short: Rectilinear locomotion or rectilinear progression is a mode of locomotion most often associated with snakes. In particular, it is associated with heavy-bodied species such as terrestrial African adders, pythons and boas; however, most snakes are capable of it.

Key takeaways

Rectilinear locomotion belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Rectilinear locomotion to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Rectilinear locomotion from memory before moving on to harder problems.

Reference excerpt

Rectilinear locomotion or rectilinear progression is a mode of locomotion most often associated with snakes. 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, 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 muscles, the costocutaneous inferior and superior, which are present on every rib and connect the ribs to the skin. 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 0.01–0.06 m/s (0.033–0.197 ft/s)), but is almost silent 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 is centered around the development of snakelike robots, 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. 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.

Illustrations

Worked examples

Example 1 — a first encounter with Rectilinear locomotion

Start with the simplest possible case. Write down what Rectilinear locomotion claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Rectilinear locomotion before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Rectilinear locomotion ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Rectilinear locomotion

In research: Rectilinear locomotion appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Rectilinear locomotion in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Rectilinear locomotion is common in secondary-school and first-year university syllabi. It links to neighbouring topics Snakes, Terrestrial locomotion, so understanding it makes those chapters shorter.
In everyday life: Look for Rectilinear locomotion outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Rectilinear locomotion in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Rectilinear locomotion means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Rectilinear locomotion out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rectilinear locomotion in simple terms?

Why does Rectilinear locomotion matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Rectilinear locomotion?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Rectilinear locomotion.