The Atlantic Mudskipper: A Fish Out of Water
Found only along the west African Cost, the Atlantic Mudskipper (Periophthalmus barbarus) is an incredibly unique species of fish. What makes it so special is that, unlike most other fish, the mudskipper can survive on land. It has several adaptations to make it semi-terrestrial. A layer of mucus over the surface of the body allows it to retain moisture, and when on land it can close its gill chambers and breathe through its skin. The eyes are set high on the head and can move independently 360 degrees, giving the Atlantic mudskipper a wide range of vision. Lastly, the pectoral fins that allow it to crawl, climb, and even skip on land, aided by a pair of pelvic fins.
P. Barbarus’ special adaptations allow it to occupy uncommon habitats within its range. It prefers semi-salty brackish water, especially at the mouths of rivers and in mudflats, although they are able to tolerate a range of temperatures and salinity. They can also be found in mangrove forests and lagoons, where they can climb up onto the roots of trees. Along the coast, individuals are most often visible at low tide when they climb up on the shore to feed. In these regions the Atlantic mudskipper digs burrows in which they can hide during high tide. To blend in, they are usually tan to dark brown with dark mottling along the back and bright blue spots on the cheeks.
During the day, the Atlantic mudskipper spends most of its time feeding and defending its territory. They are carnivorous fish, preying on crustaceans, insects, and small fish. The mouth of P. barbarbus is specially shaped so that it covers its prey with water, then sucks the water back up with its accompanying meal. When threatened by terrestrial predators such as shore birds, the Atlantic mudskipper lives up to its name and will ‘skip’ away. These fish also use their mouths in fights, which are quite common. Individuals typically guard of about 1m around their burrow. Males are especially territorial, and will fiercely guard burrows and mates from competitors. Despite their ferocity, Atlantic mudskippers are not very large; most only grow to be 14-16cm long.
Mating occurs year round, although peak times are between February and May. Males engage in territorial displays, after which females will select a male and enter his burrow to lay eggs. Clutches can easily number in the thousands, although few survive to adulthood. The male guards the burrow and, after a brief incubation period, floods it to induce hatching. Larvae drift for 1-2 months before metamorphosing into a juvenile stage, at which time they begin to return to land. Individuals reach sexual maturity at about 10.2-10.8 cm in length, roughly 1 year after hatching, and can live up to 5 years in the wild.
Conservation status: The IUCN rates the Atlantic mudskipper as Least Concern, although populations are declining. Their primary threats are from over-fishing and by-catch, pollution, and urban development. Some areas within their region have instituted sustainable fishing practices and established protected reserves as part of conservation efforts for this species.
Photos
Eva Mártensson
Eric Verhagen
Pedro Martins (via iNaturalist)
Rogerio Ferriera