The Arctic Sedge-Slider is a large, slow-moving, herbivorous bipedalien from the tundra around Glacier Cap North, very close to the glacier itself, on Darwin IV. They can produce exceptionally/extremely loud pings that can travel for a number of kilometers. Barlowe encountered a trio a few kilometers from the crash site of the late Dr. Ysud and Ysire the Yma xenogeologists in 2359 during the First Darwinian Expedition.
Traveling in small groups, sedge-sliders' enormous pink biolights shine like lanterns in the gloom of a receding storm. At first they appear headless, but as the sky grows lighter small dark beaks appear from beneath their anterior flaps. These gradually extend until an entire head is visible. The newly-emerged black heads steam for a few moments in the frigid air until they cool off. These large creatures have evolved a unique means of keeping their bare heads protected during arctic storms, by retracting them deep into their insulated body cavities.
Sedge-sliders are anything but quick, pulling their 10-meter-tall bodies across the crunchy ground with laborious strokes of their huge, hooked feet. They are among the noisiest animals found on Darwin IV, slamming out their pings with deafening regularity.
The sedge-slider's shovel-like beak can break through frozen ground to dig snowbulbs from under the tundra. The hooked feet are equally adept on ice and boggy ground. The creature's head is fully retractable, a unique and valuable adaptation in this region of sudden, killing storms.
The sedge-sliders are placid animals, digging peacefully in the frozen arctic soil for the subterranean snowbulbs that comprise their diet. As they move along there is the impression, when looking at the ground behind them, that some indecisive paleontologist has been at work, digging here and there and leaving shallow holes all about.
Because of the proximity of the glacier, the sedge-slider has developed the ability to ricochet sonar signals off the ice wall; in fact, this seems to be its preferred means of echolocation. While a group of sedge-sliders feeds, one of them is always stationed near the glacier wall bouncing its pings off into the tundra while the other individuals remain silent. Sonar analysis indicates that these are not single but multiple pings that reach into a number of directions simultaneously. The complexity of the retuned signal must be considerable, explaining the huge sonar bulge atop the creatures' bodies. Nature, as opportunistic as ever, has taken full advantage of the glacier and its acoustic capabilities.
A clever arctic Bolt-tongue can catch any sedge-slider unawares.
The high, humped back of the sedge-slider contains its sonar bulge - one of the largest of any creature on Darwin IV. It is almost a second brain.