1Shocking as it seems, cannibalism is common in the animal world. 2In species such as the red-back spider, the black widow spider, the praying mantis and the scorpion, the female commonly eats the male.3Another widespread form of cannibalism is size-structured cannibalism, in which large individuals consume smaller ones.4Octopus, bats, toads, fish, monitor lizards, salamanders, crocodiles, spiders, crustaceans, birds, mammals, and a vast number of insects have been observed to engage in size structured cannibalism. 5Yet another common form of cannibalism is infanticide. 6Classic examples include chimpanzees, where groups of adult males have been observed to attach their infants; and lions where adult males commonly kill infants when they take over a new harem after replacing the previous dominant males. Which sentence states the main idea of the paragraph?