Why does a crab walk sideways?
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"Crabs walk sideways due to their unique anatomy, which features a flattened body and legs positioned on the sides, making lateral movement more efficient. This sideways gait also helps them navigate through their natural habitats, like crevices and rocky terrain.
animal-club.co.uk''''

Interestingly...crab body form was "invented" by evolution many times over in a process called
carcinization (in American spelling).
https://en.wikipedia.org/wiki/CarcinisationOne has to wonder that when we would see a first life form on a distant planet..it would likely be a crab (or something similar).
Nice!!!
Evolution is the Key on universe!
The adoption of a crab-like body structure can convey a number of selective advantages for crustacean species. Carcinisation is associated with a lowered center of gravity, allowing these creatures to invest in sideways walking. This evasive adaptation is particularly useful in an ocean environment with forward-moving predators.