In this paper, we propose an algorithm to randomly generate a directed
animal. Directed animals are well-known combinatorial objects and hav
e been widely used for modelling the physical phenomenon of percolatio
n. The algorithm consists of three steps, and we prove that each of th
em is performed in linear time. Finally, we report the results of our
experiments made by means of appropriate computer programs in order to
give empirical evidence that our algorithm really works.