The oceans are filled with fish. However, some fish species have evolved to survive on land. The mudskipper is an amphibious fish, meaning it spends some time in the water and some time on land. In fact, mudskippers spend about three quarters of their time on land. But how do they do it?
How do mudskippers breathe on land?
All fish have gills to help them breathe in the water. Gills are made up of lots of thin structures called lamellae. Oxygen from the water can move into these lamellae. The lamellae contain blood which then carries oxygen around the fish’s body. Animals need oxygen for respiration – the process which converts food into energy for the animal. Gills have to be wet to work, which is why most fish can’t survive for more than a few minutes on land.
The mudskipper has evolved two solutions to this problem. When the mudskipper leaves the water, it tightly shuts its gill chambers (the spaces where its gills are found) and traps an air bubble inside. This stops the gills from drying out, meaning the gills still work on land. This means oxygen can keep moving into the gills, even though the fish is not in the water.
Mudskippers have evolved another way to breathe on land. Mudskippers can breathe through their skin! When mudskippers are wet, oxygen can move into their body through their skin and the lining of their mouth and throat. This means it is very important for a mudskipper to stay wet when it is on land. This way of breathing is called cutaneous air breathing. Amphibians, like frogs and toads, breathe in the same way.
How do mudskippers move on land?
Mudskippers skip across wet mud using their pectoral fins (two fins found on their sides). Most fish use their pectoral fins to help push them through the water as they swim. In mudskippers, the pectoral fins work like legs by pushing off from the ground to help the fish skip across the mud. This behaviour is what gives mudskippers their name.
What do mudskippers do on land?
To help them stay wet and cool during the day, mudskippers use their mouths to dig deep burrows in the mud. These burrows are where the fish keep their eggs whilst they wait for them to hatch.
During the mating season, male mudskippers use their pectoral fins and tails to jump high into the air. Some males can jump as high as half a metre! This attracts nearby females for the male to mate with.
Where do mudskippers live?
Mudskippers live in the intertidal zone in many parts of the world, including Africa, Asia and Australia. The Atlantic mudskipper can be found throughout much of West Africa, including in Angola, Cameroon, Ghana and the Republic of Gambia.