Friday, January 9, 2009

A walking fish – Mud Skipper
Mudskippers are the fish that have become adapted to an amphibious lifestyle. They are common on tidal mudflats throughout tropical Africa, Asia and Australasia where they crawl about out of water feeding on small animals and algae. Commonly known as mudskippers, their scientific name, Periophthalmus, refers to their ability to see in all directions with their protruding eyes. They are extraordinary members of the goby family of small tropical fishes. Well suited to an extreme range of habitats, their adaptive figures include two dorsal fins and ventral fins, more or less united. A tapering tail provides the flipping, but the crawling is dependent on front fins with muscular stalks that give an effective imitation of forelegs. Some use their ventral fins as a kind of suction cup or claspers with which to cling to a vertical surface, such as mangrove root, while watching for food or a mate. The dorsal fins differ in color pattern and development from one species to another, an d are flicked up like flags on display or lowered flush with the back, like a signal system to others of the same species.
They grow generally six to eight inches long; mudskippers belong to a mudflat community where salt and fresh water meets. They have a body that tapers backward from a massive head, and a low crosswise mouth with thin lips beneath a pair of nostrils. In all situations, the fish raises its eyes close together, moving them constantly to keep independent watch on the surroundings. At intervals a mudskipper blinks, bulging its eyes into its mouth much as a frog or toad might do, renewing the moisture that keeps them well wetted. The body is so well camouflaged with streaks of mud that birds have difficulty capturing mudskippers for their meals. The fish has every chance to see a bird coming, and if it senses danger, it skips away over the mud, leaping nearly three feet at a time, into some hole or the nearest water. So agile are they that a person on the slippery mud has difficulty catching a mudskipper by hand.
During the mating season in June and July, these males court whatever females of their kind invade the territory. Flipping his whole body into the air with all fins expanded, each male advertises his readiness to have any willing female enter his water-filled hole as a place to spawn. There he can fertilize her eggs and start a new generation. As the water rises with the returning tide, he closes the hole with mud to make a brood chamber. She helps, using her mouth to add to the surrounding wall of mud and mucus until it is about an inch high.

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