Why do Crabs Walk Sideways?

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Crabs: Their sideways shuffle and the science behind it

You might have seen athletes running sideways. One creature on the beach comes into notice due to its unusual way of walking. You guessed it right; it’s the crab, moving sideways with a peculiar shuffling motion. But why is it that crabs walk sideways, unlike most animals who move forward? This article aims to unravel this interesting facet of crab behavior.

Crab on Beach
Crab Walking on Beach, Credit: Wikimedia/Pratishkhedekar

Why do crabs walk sideways?

At the heart of the crab’s sideways movement is its unique body structure. Shaped broader than it is long, a crab’s body doesn’t lend itself well to forward motion. Now, picture yourself trying to walk sideways. It’s much harder than moving forwards, right? But for crabs, it’s quite the opposite. Their bodies are designed for sideways mobility.


Unlike our legs, which are beneath our bodies, a crab’s legs are on the side. They also have two joints on their legs, and the second joint moves sideways. This is very similar to how our knees work. except that it works sideways. This leg structure, combined with their broad body, facilitates efficient sideways movement.

Crab Close-Up
Crab's Body Structure, Credit; Wikimedia/Hans Hillewaert

Why moving sideways is actually quite handy?

Sideways movement isn’t just a quirk of crabs; it also serves some practical purposes. One big advantage of walking sideways is it can help crabs escape predators quickly. If they sense danger, crabs can zip sideways into a hiding spot, making it difficult for predators to track their path.


Crabs often live in environments where space is at a premium— bustling rock pools or crowded coral reefs. In these packed conditions, being able to navigate sideways is a real boon. It allows crabs to squeeze through gaps and weave around obstacles, a feat that forward movement wouldn’t easily permit.

Sideways motion: More than just a walk

The sideways movement of crabs isn’t just about locomotion . It’s also a form of communication. Like many animals, crabs can be quite territorial . They utilize their distinctive sideways motion to convey messages to other crabs. By moving in a particular way, a crab might signal to a fellow crab that it’s entering its territory, akin to a ‘keep out’ sign. This fascinating use of motion illustrates how crabs interact and express themselves in their underwater world.


The sideways walk of crabs isn’t a random quirk but a well-adapted trait that has enabled their survival over millions of years. It’s an ingenious solution to the challenges of their environment, from predator evasion to navigation in crowded habitats.

Crabs in Rock Pool
Crabs in a Crowded Habitat, Credit: Wikimedia/W.carter


Locomotion: The act or ability of an organism to move from one place to another. In this article, it refers to the crab’s unique way of moving, i.e., sideways walking.


Territorial: This term refers to animals’ instinct to claim a specific area or territory and defend it from others. In the context of this article, it describes crabs’ behavior of marking and protecting their own space.


Predator: An animal that naturally preys on others. In this blog, it refers to the animals that hunt and eat crabs.


Environment: The surroundings or conditions in which a person, animal, or plant lives or operates. Here, it describes the natural habitat of crabs, like rock pools and coral reefs.


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