What fish can come out of the water and walk on land?

Table of Contents

Several remarkable fish species have evolved the ability to venture onto land. The Mudskipper is perhaps the most well-known, but other species such as the walking catfish and various eels also exhibit this extraordinary adaptation, allowing them to exploit terrestrial environments for food and evade predators.

Introduction: Life on Land and in the Sea

The transition from aquatic to terrestrial life is one of the most significant evolutionary leaps in the history of our planet. While amphibians are often considered the first vertebrates to conquer land, some fish species have independently developed the remarkable ability to leave the water and, to varying degrees, “walk” on land. This adaptation, driven by environmental pressures and the pursuit of resources, showcases the incredible plasticity of life and the enduring quest for survival. What fish can come out of the water and walk on land? is a question that reveals a fascinating intersection of evolutionary biology and ecological adaptation.

The Star of the Show: Mudskippers

Mudskippers are arguably the most iconic examples of fish capable of terrestrial locomotion. These amphibious gobies inhabit intertidal mudflats and mangrove swamps across the Indo-Pacific region. Their anatomy and behavior are perfectly suited for a life that straddles the aquatic and terrestrial realms.

Modified Pectoral Fins: Mudskippers possess strong, muscular pectoral fins that they use to “walk” or “skip” across the mud. These fins act like miniature arms, allowing them to propel themselves forward with surprising agility.
Air Breathing: They are able to breathe air through their skin, which is highly vascularized, and through the lining of their mouth and pharynx. They also gulp air and hold it in their opercular chambers.
Eye Adaptations: Their eyes are located high on their head and can move independently, providing a wide field of vision both above and below water. They also have specialized eyelids that keep their eyes moist.
Burrowing Behavior: Mudskippers construct and inhabit burrows in the mud, which they use for shelter, reproduction, and to maintain moisture.

Other Notable Land-Walking Fish

While Mudskippers may be the poster children for land-walking fish, they are not alone in their terrestrial endeavors. Several other species exhibit varying degrees of amphibious behavior.

Walking Catfish: These catfish, native to Southeast Asia, have the ability to “walk” short distances on land using their pectoral fins and by wiggling their bodies. They can survive out of water for extended periods thanks to their accessory respiratory organs, which allow them to breathe air.
Eels: Some species of eels, particularly freshwater eels, can move overland, especially in wet conditions, to reach new bodies of water or to escape unfavorable environments. Their elongated bodies and muscular movements allow them to slither across the ground.
Snakeheads: Certain species of snakeheads (Channidae) are known to move between bodies of water, particularly during periods of heavy rain. They can breathe air and use their pectoral fins to propel themselves forward.

Why Do Fish Walk on Land?

The reasons what fish can come out of the water and walk on land are diverse, but the primary drivers are related to survival and resource acquisition.

Food Availability: Intertidal zones and mudflats are often rich in food sources, such as insects, crustaceans, and algae. Walking on land allows fish to access these resources that are unavailable to strictly aquatic species.
Predator Avoidance: Escaping aquatic predators is another major benefit of terrestrial locomotion. By venturing onto land, fish can avoid predation pressure from larger fish or other aquatic animals.
Territorial Defense: Mudskippers, in particular, use their terrestrial abilities to defend their territories and attract mates. Males often engage in elaborate displays on land, including fin flapping and jumping.
Finding New Habitats: During droughts or floods, some fish may be forced to leave their current habitat in search of new bodies of water. The ability to walk on land can be crucial for survival in these situations.

Challenges of Terrestrial Life

Transitioning to land presents several challenges for fish, including:

Desiccation: Fish are adapted to living in water, and they can quickly dehydrate in dry air. Amphibious fish have evolved various mechanisms to minimize water loss, such as specialized skin and behavioral adaptations like burrowing.
Gravity: Water provides buoyancy, which supports the body of a fish. On land, fish must support their own weight, requiring stronger bones and muscles.
Respiration: Fish gills are designed to extract oxygen from water. Amphibious fish need to supplement their gill respiration with air breathing.
Locomotion: Moving on land requires different types of muscles and skeletal structures compared to swimming. Amphibious fish have evolved specialized fins and body movements for terrestrial locomotion.

The Evolutionary Significance

The ability of some fish to walk on land provides valuable insights into the evolution of tetrapods (four-limbed vertebrates). These fish may represent an intermediate stage between fully aquatic fish and terrestrial amphibians, offering clues about the evolutionary pressures and adaptations that led to the colonization of land by vertebrates. Understanding what fish can come out of the water and walk on land helps us understand our own evolutionary history.

Frequently Asked Questions

What is the most well-known fish that can walk on land?

The Mudskipper is the most widely recognized and studied fish capable of walking on land. Its unique adaptations, including modified pectoral fins for locomotion and the ability to breathe air, make it a fascinating example of amphibious evolution.

How do Mudskippers breathe when they are out of water?

Mudskippers can breathe through their skin, which is highly vascularized. They also gulp air and hold it in their opercular chambers, which are specialized pouches that act like makeshift lungs.

Can Walking Catfish really walk?

While they don’t “walk” in the traditional sense, Walking Catfish can move across land using their pectoral fins and by wiggling their bodies. This allows them to migrate between bodies of water, especially during periods of heavy rain.

What kind of environment do land-walking fish typically live in?

These fish typically inhabit intertidal zones, mangrove swamps, and freshwater habitats that are subject to fluctuating water levels. These environments provide opportunities for both aquatic and terrestrial foraging.

Why is it important for fish to be able to breathe air?

Air breathing allows fish to survive in oxygen-poor water or when they are out of water. This is particularly important in shallow, stagnant water where oxygen levels can be low.

How do Mudskippers keep their eyes moist when they are on land?

Mudskippers have specialized eyelids that help to keep their eyes moist. They also roll their eyes back into their sockets to rehydrate them.

Are there any dangers for fish when they are out of the water?

Yes, being out of water exposes fish to the risk of dehydration and predation from terrestrial animals. They are also more vulnerable to temperature fluctuations.

What adaptations allow eels to move on land?

Eels have elongated, muscular bodies that allow them to slither across the ground. They also secrete mucus that helps to keep their skin moist.

How does the ability to walk on land help fish find food?

Walking on land allows fish to access food sources that are unavailable to strictly aquatic species, such as insects, crustaceans, and algae in intertidal zones.

Do all types of eels walk on land?

No, not all eels walk on land. Only certain species, particularly freshwater eels, exhibit this behavior, usually when migrating between bodies of water or escaping unfavorable conditions.

Are there any walking fish native to North America?

While not as proficient as Mudskippers, the Northern Snakehead, an invasive species, has been found in North America and is known for its ability to move across land, particularly in wet conditions. This makes it a concern for native ecosystems.

Could land-walking fish have been ancestors to land animals?

The characteristics of what fish can come out of the water and walk on land suggest that they may represent an intermediate stage between aquatic fish and terrestrial amphibians. However, they are not direct ancestors to modern tetrapods; rather, they illustrate convergent evolution—the independent evolution of similar traits in different lineages.