An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures.[1] An alternate term is entomophage[2]:455, which also refers to the human practice of eating insects.
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.[3]
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Although individually small, insects exist in enormous numbers - they number over a million described species[4]:1958 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.[5]:13 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.[6]
Examples of insectivores include nightingales, aardwolfs,[7] echidnas,[8] swallows, anteaters, carp, frogs, lizards, bats, and spiders. Even large mammals are recorded as eating insects;[6] the sloth bear is perhaps the largest insectivore. Insects also can be insectivores; examples are dragonflies, hornets, ladybugs, and praying mantises.[9]:31 Insectivory also features to various degrees amongst primates, such as marmosets, tamarins, tarsiers, galagos and aye-aye.[10][11]:56-57 There is some suggestion that the earliest primates were nocturnal, arboreal insectivores.[12]
Insectivorous plants are plants that derive some or most of their nutrients (but not energy)[13]:14 from trapping and consuming animals or protozoans, typically insects and other arthropods. Also known as carnivorous plants, they appear adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs and rock outcroppings.[13]:13 Insectivorous plants include the Venus flytrap, several types of pitcher plants, butterworts, sundews, bladderworts, the waterwheel plant, brocchinia bromeliads, and others. These plants obtain nitrogen by trapping insects. They use a variety of mechanism such as pitfalls, sticky surfaces, hair-trigger snaps, bladder-trap and lobster-pot trap mechanisms.[13]:14-17
Technically these plants are not strictly insectivorous, as they consume any animal small enough to be trapped by them; indeed, the larger varieties of pitcher plant have been known to consume small rodents and lizards.[13]:13 Charles Darwin wrote the first well-known treatise on carnivorous plants in 1875.[14]
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