While fish are typically associated with aquatic environments, some species possess the remarkable ability to move and survive outside of water. This adaptation challenges conventional notions of fish behavior, revealing diverse strategies for navigating terrestrial landscapes.
Fish That Can Move on Land
Mudskippers, for instance, are highly specialized amphibious fish that spend more time on land than in water. They are found in tropical and subtropical intertidal zones, often seen hopping across mudflats. Walking catfish, native to Southeast Asia, utilize their rigid pectoral fins to “walk” across land, sometimes covering distances of up to three-quarters of a mile, especially during periods of high stormwater runoff. Lungfish, such as the Australian lungfish, survive out of water, using modified swim bladders that function as lungs. Climbing perch, found in East Asia and Africa, can move on land during rainy weather, using their gill covers and fins for propulsion as they seek new water bodies. The mangrove rivulus can even live out of water for months, breathing air through its skin while seeking moist, sheltered places like hollow logs when swamps dry out.
How Fish Move Out of Water
Mudskippers use their strong, jointed pectoral fins, which resemble limbs, to propel themselves in a hopping motion across the mud. They can even climb trees, sometimes aided by suckers on their fins. To breathe on land, mudskippers absorb oxygen through their skin and by keeping their gills moist with water stored in a specialized organ. Walking catfish use their rigid pectoral fins as stilts, enabling them to literally walk over dry land. They possess a specialized air-breathing apparatus within their gills, allowing them to survive for hours outside of water in humid conditions. Climbing perch use their gill covers and fins in a coordinated manner, along with tail propulsion, to move across land. Some species, like the mangrove rivulus, can breathe directly through their skin and gills while on land.
Reasons for Land Movement
The ability of fish to move onto land is driven by various environmental pressures and offers significant survival advantages. Escaping unfavorable aquatic conditions, such as oxygen-poor water or drying habitats, is a common motivation. For instance, when their water sources dry up, walking catfish will venture onto land to find new pools.
Moving onto land also allows fish to escape aquatic predators, access new food sources like insects, and migrate to new bodies of water. This behavior has evolved repeatedly across different fish families, suggesting it is a successful strategy for survival and colonization of new territories.