are members of the subfamily Oxudercinae
), within the family Gobiidae
). They are completely amphibious
fish, uniquely adapted to intertidal habitats
, unlike most fish in such habitats, which survive the retreat of the tide
by hiding under wet seaweed
or in tidal pools
. Mudskippers are quite active when out of water, feeding and interacting with one another, for example to defend their territories
They are found only in tropical and subtropical regions, including all the Indo-Pacific and the Atlantic coast of Africa.
Compared with fully aquatic gobies, these fish present a range of peculiar behavioural and physiological adaptations
to an amphibious lifestyle. These include:
- Anatomical and behavioural adaptations that allow them to move effectively on land as well as in the water.
- The ability to breathe through their skin and the lining of their mouth (the mucosa) and throat (the pharynx). This is only possible when the mudskipper is wet, limiting mudskippers to humid habitats and requiring that they keep themselves moist. This mode of breathing, similar to that employed by amphibians, is known as cutaneous air breathing. Another important adaptation that aids breathing are their enlarged gill chambers, where they retain water. These large gill chambers close tightly when the fish is above water, keeping the gills moist, and allowing them to function. They act like a scuba diver's oxygen cylinders, and supply oxygen for respiration also while on land.
- Digging of deep burrows in soft sediments that allow the fish to thermoregulate; avoid marine predators during the high tide when the fish and burrow are submerged; and for laying their eggs.
Even when their burrow is submerged, mudskippers maintain an air pocket inside it, which allows them to breathe in conditions of very low oxygen concentration.
The genus Periophthalmus
is by far the most diverse and widespread genus of mudskipper. Seventeen species have been described. Periophthalmus argentilineatus
is one of the most widespread and well known species. It can be found in mangrove ecosystems
of East Africa
east through South East Asia
to Northern Australia
, southeast China
and southern Japan
, up to Samoa
It grows to a length of about 6 in (15 cm) and is a carnivorous
opportunist feeder. It feeds on small prey such as small crabs
and other arthropods
. Another species, Periophthalmus barbarus
, is the only oxudercine goby that inhabits the coastal areas of western Africa (Murdy, 1989). Both of these mudskippers are widely traded as aquarium fish, but are very difficult to keep alive in captivity as they require a special tank design and a variety of living prey. Due to their amphibious habits, they are completely unsuited for normal fish tanks.