Fish, with their streamlined bodies and strong tail fins, are built perfectly to propel themselves rapidly through water. Their body muscles contract from side to side and front to back to move them in a way that pushes against the water, while fins on their sides stabilise them.
But there are a handful of species that defy convention and use fins as makeshift legs; others slither across land, and some can even climb. Here are some of the most astonishing fish that have evolved the ability to walk – on land, seabeds and even up rocks.
Fish that can walk
Mudskipper
The boggle-eyed mudskipper (Oxudercinae) is part of the goby family and amazingly spends most of its time on land. There are 23 different species found in the Indo-Pacific regions, in countries such as Japan and Australia, often in tidal flats and estuaries.
Mudskippers have adapted to breathe through their skin and the lining of their mouth and throat. They make sure they don't dry out in the sun by regularly rolling in the mud, or tunneling underneath it. They have incredibly strong pectoral fins that help them propel themselves along the land. Eyes on the top of their head helps them to spot predators as well as potential mates.
Lungfish
In freshwater, these strange strollers walk on long, fleshy fins, moving their left and right fins in an alternating pattern, similar to how animals walk with limbs. Some researchers believe this incredible trait suggests it evolved before animals made the full transition to land.
The lungfish (Dipnoi) can breathe air, and on land its walk turns into more of a belly crawl.
Longlure frogfish
This strange-looking fellow, the longlure frogfish (Antennarius multiocellatus), is capable of camouflaging itself against the coral it lives near. But that's not its only skill – it can walk, in its own unusual way. It moves along the ground and over rocks on its modified pectoral and pelvic fins. Its stealth-like movements make minimal disruption to the water, keeping it under the radar of predator and prey.
Climbing perch
Here's a fish with many talents: walking, climbing and surviving on land, to name a few. Usually found near Papua New Guinea, the climbing perch (Anabas testudineus) can move across dry land by wriggling its body and using spikes on its fins. It can survive out of water for six days and is known to migrate between ponds and wetlands during droughts.
Cave angel fish
This gravity defying Cryptotora thamicola, more commonly known as the cave angel fish, is one of the most elusive fish in the world. It's a tiny species of hillstream loach that lives in Thailand and has adapted to surviving in the dark: they are blind and are depigmented. Their pectoral fins have evolved and developed microscopic hooks that help it to climb up vertical waterfalls and cling on tight in fast-moving waters.
Walking catfish
As its name suggests, the walking catfish (Clarias batrachus), native to Southeast Asia, can haul itself along land using its strong body and pectoral fins. It hunts for food – insects smaller fish, eggs and plant matter – or better pools of water to live in. It has a slippery mucus that protects its skin when out of the water.
Its airbreathing abilities mean it can survive up to 18 hours out of water. It's adept at survival, and in many places, including Florida, United States, considered a highly invasive species.
Lithogenes wahari
This peculiar species of catfish, discovered in the Venezuelan mountains, shares traits with armoured catfishes and climbing catfishes. It uses its fins and sucker mouth to drag itself up rocky inclines. Its fins can move backward and forward independently, each wired to its own muscle, and has toothlike protrusions to help the fish get traction.
Epaulette shark
Did you know there's even a species of shark that walks? The epaulette shark (Hemiscyllium ocellatum), found in the western Pacific Ocean in waters around New Guinea and northern Australia, remains on the reef even when the tide goes out. It deals with having less oxygen by shutting of part of its brain so it can remain in pools to hunt food such as crabs and shrimp.
Discover more fascinating fish facts:
- Most beautiful fish: Are these species are the ocean's most stunning fish?
- What is the world's largest freshwater fish?
- How long can a fish live out of water?
- Is there really no such thing as a fish?
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