Pitfall Plumpus

The pitfall plumpus is a large, predatory lumpus evolved from the porcuplumplus, known for its unusual body shape and hunting behavior. Weighing up to 90 pounds, this tribbet is distinctive for its spiny back, with dozens of sharp spikes growing out of small pores in its flesh, some of them wickedly hooked - they are defenses, which protect them from predators. These creatures are sedentary with a low metabolism, and spend the days lying in rest, but the plumpus becomes more active at night, when it may be seen to shuffle along over the ground, striding across the savannahs of southern Serinarcta on relatively lengthy legs. It searches for a spot of suitably loose and sandy substrate where, using large forearm claws, it then digs a pit roughly 6 feet deep and around twice the width of its body. It normally situates its burrow in the middle a well-worn game trail, where herds of animals pass by, often on routes to established watering holes or where the terrain forms natural choke points, congregating herds together between natural boundaries like cliffs or ravines, in order to move from one area to another. The plumpus finishes its hole by laying branches and long stalks of grass over the top of it, entering the vertical burrow and then finishing arranging the vegetation so as to cover the entrance and obscure it from passers by. 

But this is not a simple shelter, a place to sleep the day away. For once settled in the hole, the plumpus undergoes a shocking visual transformation.  It lays down in the bottom of the pit, and there relaxes itself. Folds of muscle tissue, supported by hinged extensions of the animal's ribs, lower down at its sides until it becomes over twice its normal width. Its ribs press outward against the walls of the hole, while its spines retract into sockets in its skin. Now, wedged into place in its trap, the plumpus waits. Eventually, if it has picked a good site for its ambush, some sort of small herd animal - a snoot, or perhaps a loopalope - will come along. The trap is generally too small to catch something bigger than the plumpus, but these smaller animals are not so lucky. They stumble along into the trap, break through the cover of leaves and branches, and find themselves tumbling down right on top of the plumpus. This is exactly what it has waited for. 

The moment prey falls through the pit and onto itself, the pitfall plumpus reflexively contracts its ribs, instantly folding itself up and extending its spines, some of which may be over 6 inches in length. The prey is skewered dozens of times, squeezes between the pleated ribs as they fold together and hopelessly tangled in the spines on the plumpus' back. Now, using its long forearms, the plumpus slashes at its target as it rams its back into the walls of the pit. Prey is killed, or mortally wounded, and then pulled off of itself with the arm claws and relaxation of its spines. The plumpus then feeds on its prize for several days, burying what it does not instantly eat at the bottom of the hole to uncover again later when it is hungry once more. This strange repurposing of defensive traits into an offensive role allows this species of lumpus to catch far larger food items than otherwise it could manage, and this has also allowed the female to produce as many as four offspring at a time, which she cares for and shares her kills with for upwards of a year - one of the best mothers of all the non-tribbethere tribbets.