Killing and eating of potential competitors has rarely been documented in the zoological literature, even though this type of interaction can affect population dynamics. In a recent publication in the open-access journal Subterranean Biology, Brazilian scientists presented their notes regarding the predation of an assassin bug by a spider in Neotropical caves. Underground, where food resources are scarce, such events might be possible as a result of ecological pressures imposed by the hostile environment, hypothesise the researchers.