I am designing an alien life form adapted to an Earth-like world, descended from cuttlefish-like ancestors. It has adapted its undulating head-fin as a rippling “foot”, similar to a slug or other Gastropod’s. This “foot” differs in not adhering to the ground, but instead gripping using gecko-like pads, enabling the animal to haul itself along in a manner almost like a mudskipper, but still with the characteristic rippling motion.

Assuming this animal weighs around a kilogram, how fast could it move in the standard Earth gravity of one G?

  • $\begingroup$ How fast you would like it to go? $\endgroup$ Commented Dec 25, 2022 at 17:05
  • $\begingroup$ Not cheetah speed; perhaps a slow walking pace of 0.5 m/s. $\endgroup$
    – user98816
    Commented Dec 25, 2022 at 17:49

1 Answer 1


Gastropod muscles can work at high speed, look at the "Jumping snail"

The rippling motion is very similar to that used by snakes for "rectilinear motion" enter image description here By Chris Vynbos - source, CC BY-SA 4.0, found on wikicommons

However no animals that use this type of motion achieve speeds greater than 5cm/second. 50cm/s is not utterly unreasonable, but is beyond Earth animals.

Any slug that is capable of this kind of motion would probably move to something faster if speed was required, perhaps "looping" in the manner of a caterpillar, or serpentine motion, even sidewinding.

If you allow for the foot to come off the floor, then these other motions are much faster. having Gecko like grip would make sidewinding an attractive proposition on smooth surfaces. Snakes are generally limited by lack of grip, not lack of speed or strength.


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