An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects. As not all insectivorous mammals are closely related, the former order Insectivora is now abandoned as a biological grouping, though some remain in the order Eulipotyphla.
The first vertebrate insectivores were Amphibians. When they evolved, 400 million years ago, the first amphibians were piscivores, with numerous sharp conical teeth, much like a modern crocodile. The same tooth arrangement is however also suited for eating animals with exoskeletons, thus the ability to eat insects is an extension of piscivory.
Although individually small, insects exist in enormous numbers - they number over a million described species and some of those species occur in enormous numbers. Accordingly insects make up a very large part of the animal biomass in almost all non-marine, non-polar environments. It has been estimated that the global insect biomass is in the region of 1012 kg with an estimated population of 1018 organisms. Many creatures depend on insects as their primary diet, and many that do not (and are thus not technically insectivores) nevertheless use insects as a protein supplement, particularly when they are breeding.
Examples of insectivores include nightingales, aardwolfs, echidnas, swallows, anteaters, carp, frogs, lizards, bats, and spiders. Even large mammals are recorded as eating insects; the sloth bear is perhaps the largest insectivore. Insects also can be insectivores; examples are dragonflies, hornets, ladybugs, and praying mantises. Insectivory also features to various degrees amongst primates, such as marmosets, tamarins, tarsiers, galagos and aye-aye. There is some suggestion that the earliest primates were nocturnal, arboreal insectivores.