Let us start from the basics, almost every continent has it's own Darter and all are fairly closely related. Asia has Darter called Oriental Darter and America, Africa and Australia have the Darters named after the respective continents. That makes 'four' living species out of which three are fairly widespread and common but the fourth listed as near-threatened.
The name is Darter as the bird swims underwater and then 'Spears' the fish to impale them by its 'Dart like' beak. It then surfaces - tosses the impaled fish free - and then swallows it headfirst. To stab the fish they have strongly developed muscles in the neck at the 8th and 9th vertebrae that is used to flex and stab the fish below water.
The bird while underwater is absolutely sleek and looks like a snake or a eel propelled forward by powerful feet. These are one of those birds whose wings are not protected with wax like secretion that keeps other waterbirds wings dry. That does help maintaining the buoyancy under water but have to be dried. That is a typical sunning posture that you will find these birds in - after hunting/swimming.
|The 'Dart like' beak of the Australasian Darter|
The Australian Darter is called Australasian Darter and is found in almost entire Australia (baring the very centre) Indonesia, New Zealand and Papua New Guinea. They are fairly big birds - 85-90 cm in length and weighing almost 2.5kg. They are also called 'Snake-birds' due to the long necks and only the necks remaining above the water when swimming.
These birds inhabit freshwater or brackish wetlands more than half a meter deep with fallen trees, logs and vegetated banks. They are also found in the saltwater or estuarine environments - but less commonly.