Next time you happen to step in the mud, keep an eye out for mudskippers: fish that can walk. This curious creature is known for a number of quirky features, including its crazy-looking frog eyes and the fact that it can live out of water.

These ridiculous facts are just the beginning of mudskippers. (Remember, there are at least 25 species of mudskippers roaming around, each with their own unique qualities!) Let’s dip our toes in the mud and learn about these fascinating fish.

these fish can walk

Roaming the slushy swamps and rivers of tropical and subtropical Africa, Australia, and Asia, mudskippers (Oxudercinae family) are land-loving fish that spend as much time on land as they spend in the water, if not more. However, it’s not just a preference – oddly enough, prolonged exposure to water can even drown the fish. To prevent drowning, mudskippers tend to perch on mangrove roots and rocks all day in search of their next meal of insects, small crustaceans and worms, all while maintaining a layer of hydrated mud. Amazingly, some mudskippers can even climb trees using their pelvic fins and large (and muscular) pectoral fins shaped like legs. These legs help them move along the mud using a movement called a “cane” because it resembles a person walking on crutches. Obviously, fish that are able to “walk” are unusual, but mudskippers are not alone – the frogfish is another member of this very unique club of walking fish.

mudskipper in mudmudskipper in mud
© Mikael Milden/flickr

High jump is important, territory is critical

For many male mudskippers, the key to finding a mate is how high he can fly. Although the setting is muddy and less romantic, the high jump can get him noticed in the mudskipper dating pool. Amazingly, these fish can jump two feet above the mud, all in the name of love. Mudskippers are also very territorial, so it’s not uncommon to spot a duel between several mudskippers if neighbors get too close. Skirmishes usually involve their mouths open and their dorsal fins raised while they attack each other. Some mudskippers even emit the equivalent of a battle cry.

Their mud holes are what keeps them bound to land

These fish need a coating that keeps them moist as they run through the mud. To achieve this, some mudskipper species burrow in the mud and maintain air pockets for use when oxygen levels drop. These caves are also used for predator protection and spawning. Instead of using their torpedo-shaped bodies to dig these burrows, mudskippers scoop up dirt with their mouths and spit them out once they leave the new burrow. This burrowing method is very effective in protecting mudskippers.

Their protruding eyes are very useful

Mudskippers have two bulging eyes on their heads. The frog-like eyes are able to move independently of each other, giving this fish amazing peripheral vision. The big eyes are also retractable and can see almost 360 degrees around! At first glance, although they appear to be blinking constantly, they are actually hydrating. When they blink, their eyes retract into a fluid-filled dermal cup that keeps their eyes moist. Mudskippers’ protruding eyes help them find food in dense mud and see both underwater and above water.

This fish can “breathe” from the water

So, how can fish breathe in water? Well, for mudskippers, it’s all in gills and humidity. Mudskippers use their gill cavities to “breathe” while swabbing them with mud and filling them with water and air with their fins. This process is essential because if their gills dry out, they can no longer take in oxygen. When the gills of mudskippers fill with air, their gills swell, which gives them the appearance of puffed cheeks! The fish can also breathe through the skin like amphibians, using a method called cutaneous breathing. The process involves mudskippers taking advantage of the wet environment to their advantage. Their skin and the lining of their mouth have capillaries that allow them to absorb oxygen through the skin and breathe by rolling in moist mud.

mudskipper on the beachmudskipper on the beach
© Klaus Stiefel/flickr

If one thing is for sure, never doubt the fish that can thrive on land.

Next time you find yourself near a muddy swamp or river, be sure to keep an eye out for these land-loving fish! The mighty mudskipper is just one of the amazing and strange creatures currently roaming the planet. But like all animals, they need our help to create a cleaner environment. Check out the Marine Conservation Society’s Action Center to see what you can do to help marine animals, including fish that can walk on land.

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