It stands about 8 meters tall and is as lethal and as threatening as any bipedalien predator seen on Darwin IV. Its black-hided body is muscular and tight, and is surmounted by a large, pointed head which continuously swings back and forth in a meter-wide arc when pursuing such prey as thornbacks, Littoralopes, Gyrosprinters and prismalopes. With each swing it emits a pair of shrill, grating pings that target fleeing prey. Darting from its bony head is a red arrow-tipped tongue, serrated and glistening with saliva, which gives the animal its common name. A mostly solitary hunter, the arrival of its dark form upon the plains presages a short and furious pursuit almost always ending in the death of some hapless prey animal. Jetdarters will often follow arrowtongues, sensing an imminent kill to scavenge on.If a retreating prey animal, or two, loses its footing on the loose rocks, then the arrowtongue has a chance. The arrowtongue, for all its bulk, is enormously quick and is upon its prey before the stunned victims can regain their feet (though its smaller relative, the rayback, is faster it). Its tongue lashes out and spears a prey animal with such ferocity as to send a geyser of dark blood a meter into the air. The prey collapses with a gurgling sigh as its killer quickly retracts its tongue, turns and with a flick of its head, knocks a possible second prey item sprawling.
The red blur of the predator's tongue finds its mark: and now, without withdrawing the organ, it crouches down and begins to feed. Powerful muscles ripple on the arrowtongue's sides and throat as it sends powerful digestive juices into the prey's body (usually into the chest cavity), and then withdraws the liquefied contents. Over the next half hour this process is repeated several times until the juices have completely cleaned organs out of the dead prey animal's body. Apparently the arrowtongue's diet consists of only the broken down viscera of its victims, for it leaves the prey's carcass intact for the scavengers.
It might do this process immediately again with another caught prey animal. Again, the arrowtongue will insert its tongue. After another half hour, its belly distends, the glutted creature rises somewhat unsteadily and slowly strides off about 20 meters or less then lies down and rests. These are typically successful hunts and the fortunate arrowtongues can sleep through the night.
This aggressive liquivore is frequently spotted concealing itself amongst the electrophyte beds, taking advantage of the colonial plants’ electrical discharges to discourage the herds from approaching too closely. It is believed that the creature emits its ranging pings in concert with the electrophytes’ discharges, a habit that probably obscures its point of origin from prey animals.At times, arrowtongues will gather in groups to accompany keeled grove-backs to prey on whatever they stir up (as was first observed late one night in the Sinus Columbus during the First Darwinian Expedition). A predictable side effect of the travels of so large a creature as the grove-back is the flushing of enormous quantities of game. The arrowtongues opportunistically follow the huge beast, preying upon this game (even at great risk to themselves being crushed).
Short moments after a grove-back's death, an arrowtongue appears, the first of many opportunistic liquivores to arrive at this easy banquet.
Despite its power and ferocity, an arrowtongue can itself be prey to skewers and Eosapiens, the latter of which will sometimes wrench the long, barbed tongue off of an arrowtongue after they have already killed it.
- In the documentary adaptation, the arrowtongue's size was changed from 8 meters tall to 8 feet tall.