MUD SKIPPER

A mudskipper is any of the numerous species of amphibious fish belonging to the subfamily Oxudercinae. These fish derive their name from their habit of “skipping” across mudflats and burrowing into soft sediment. Their remarkable ability to walk and breathe on land distinguishes them from most other species of fish. In fact, they find it easier to hunt on land than in water. They range throughout the tropical, subtropical, and temperate waters of the Atlantic and Indo-Pacific Oceans.

Mudskippers are unique-looking fish with elongated bodies, protruding eyes on the tops of their flat heads, and prominent pectoral fins located far forward on their bodies. They use these fins to “walk” on land, “skip” across muddy flats, and even climb low vegetation. In color, they tend to be either dark or light brownish-green. Their specialized gills enable them to breathe air as long as they retain water inside their gill chambers. The lining of their mouths and throats also enables them to absorb oxygen. In size, these fish grow up to 11 inches in length with the giant mudskipper (Periophthalmodon schlosseri) being the largest species. Unlike most other fish, mudskippers blink. They do this to keep their eyeballs moist when out of water.

Mudskippers range throughout the Indo-Pacific region including areas of Africa, Asia, and Oceania. In addition to this, they also live along Africa’s Atlantic coast. Depending on the species, mudskippers can survive in marine, brackish, and freshwater environments. They inhabit a variety of habitats including oceans, estuaries, swamps, and mudflats. They dig burrows in intertidal zones to thermoregulate, hide from predators, and lay their eggs.

The IUCN includes several species of mudskippers on its Red List of Threatened Species including the giant mudskipper, the slender mudskipper, and the kalolo mudskipper. It currently assigns them the status of Least Concern.

Evolution and History

The first tetrapods (land-dwelling vertebrates) appear to have evolved about 395 million years ago between the Devonian and Carboniferous Periods. Scientists believe the unusual amphibious adaptations of mudskippers may offer clues to this crucial period of evolution. However, the fossil record from this time is extremely sparse.

One of the mudskipper’s notable adaptations is its lack of a fleshy tongue. To swallow, it uses mouthfuls of water both to suck in its prey and guide it to the back of its throat. This allows it to eat on land. Some scientists speculate that this adaptation played a role in allowing water-dwelling animals to transition to land hundreds of millions of years ago.

Predators and Prey

Mudskippers are carnivorous fish that come up on land to feed. This is due to their difficulty in catching prey while in water. Before moving onto dry land, each individual mudskipper takes in a mouthful of water to use as a “hydrodynamic tongue.” On land, it pounces on its prey, expelling some of the water in its mouth. After the water surrounds its prey, it sucks the water back in, drawing the animal in with it. The water also acts as a tongue that enables the swallowing mechanism by guiding the prey to the back of the mudskipper’s mouth.

What Do Mudskippers Eat?

Fish within this subfamily consume small crustaceans like crabs as well as snails, worms, and various insects. Some reports also describe them as occasionally cannibalistic.

What Eats Mudskippers?

These fish have a number of predators both on land and in the water. On land, these include various mammals, snakes, and shorebirds like herons and kingfishers. In the water, their predators include larger predatory fish and water snakes.

Reproduction and Lifespan

During spawning season, male mudskippers compete for females by leaping as much as two feet in the air and posturing. The successful male accompanies the female into her burrow, which she digs by scooping up mud in her mouth and flinging it away. Once the female lays her eggs, potentially hundreds at a time, the male fertilizes them. Shortly thereafter, the female leaves the male alone to guard the eggs.

During low tide, the parental guardian transports mouthfuls of air into the burrow to aid embryonic development. When the embryos have completed their development, the guardian then removes the air from the burrow to facilitate the entry of water during a nocturnal rising tide. The incoming water induces hatching.