Original title: Mudskippers use tail thrusting to help crutching to move on mud of various wetness
Divya Ramesh, Gargi Sadalgekar, Jiangqi Tan, Chen Li · September 2026
Amphibious fish face a tough challenge when moving on mud. Wet mud can act like a solid or flow like a liquid, changing how easily it breaks and how sticky it gets. Researchers tested mudskippers on clay mud with different amounts of water across this solid-to-fluid range. When mud was wetter, its strength dropped by 100-fold. This caused mudskippers to sink deeper, forcing more of their bodies and fins against the muck. More mud stuck to the fish and pulled against them on wetter surfaces, while the mud was stickiest at intermediate wetness. On dry mud, dried fish mucus made mud stick to fins. To keep moving, mudskippers mainly used a standard crutching walk, using their fins like crutches, with only a modest drop in performance. When crutching struggled, they bent and straightened their tails downward and backward to push, jump, and generate extra lift and thrust.
Imagine walking on a beach where the sand changes from dry to wet. When the sand is wet, your feet sink deeper and the sand sticks to your shoes, making it harder to lift your feet. You might start using your hands to help pull yourself forward. If that still isn't enough, you might push with your other leg to jump. Here, the mudskipper uses its front fins to push itself forward like crutches, and when that becomes less effective on wetter mud, it uses its tail to push down and back to generate additional thrust.
This study reveals how mudskippers, amphibious fish living at the water-land interface, cope with mud that varies from solid to liquid. Understanding their locomotion can inspire robots designed for wet, unstable terrain and deepen our knowledge of how animals transition between water and land.
The study only examined mudskippers on clay mud, so it is unclear if these findings apply to other amphibious fishes or other muddy substrates. The abstract does not quantify the effectiveness of tail thrusting or compare it to other strategies.
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Mudskippers use tail thrusting to help crutching to move on mud of various wetness — Divya Ramesh, Gargi Sadalgekar, Jiangqi Tan et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.