This is a list of herbivorous animals, organized in a roughly taxonomic manner. In general, entries consist of animal species known with good certainty to be overwhelmingly herbivorous, as well as genera and families which contain a preponderance of such species.
Herbivorous animals are heterotrophs, meaning that they consume other organisms for sustenance. The organisms which herbivores consume are primary producers, predominantly plants (including algae). Herbivores which consume land plants may eat any or all of the fruit, leaves, sap, nectar, pollen, flowers, bark, cambium, underground storage organs like roots, tubers, and rhizomes, nuts, seeds, shoots, and other parts of plants; they frequently specialize in one or a few of these parts, though many herbivores also have quite diverse diets.
List criteria Animal diets are not inflexible, and most animals will stray from their typical diet on occasion; for instance, cattle will eat chicks, and crocodiles will consume fruit. Though it can be hard to determine what is a true aberration, as opposed to being a normal, but minor component of the diet, animals are still regarded as herbivores, carnivores, or otherwise as long as the vast majority of their diet reflects such a categorization. Thus, several of the animals which appear on this list are commonly described as omnivores, but, where consumption of animal matter is marginal, they meet the criteria for inclusion. These cases are elaborated upon within the article.
Where quantifiable data to support such an evaluation exist, this list generally includes animals whose diets are at least ~90% herbivorous, as a simple and arbitrary minimum, though a great many listees are far more herbivorous than this; perhaps the majority are closer to 95%, and a large number are nearly purely herbivorous. However, a small selection of taxa which are not usually this herbivorous also receive mention; typically, this is done when the animal is much more herbivorous than the vast majority of close relatives. For example, the maned wolf receives mention; its diet varies from mostly carnivorous to overwhelmingly frugivorous, being mostly a fairly balanced omnivore overall, but they are still listed because no other living Canid is nearly so herbivorous. Other animals may receive mention if at least some populations of the species regularly consume very plant-heavy diets.
The issue is further complicated by variation based on region, sex, age, season, and other factors, as well as differing techniques for measuring dietary proportions and a lack of data on many species. A number of listed taxa also consume a significant quantity of fungi. On the whole, however, this list consists almost entirely of animals which are known with good certainty to be overwhelmingly herbivorous, with exceptions being noted.
Invertebrates Insects Herbivory is of extreme ecological importance and prevalence among insects. Perhaps one third (or 500,000) of all described species are herbivores. Herbivorous insects are by far the most important animal pollinators, and constitute significant prey items for predatory animals, as well as acting as major parasites and predators of plants; parasitic species often induce the formation of galls. Herbivorous insects also form symbioses with numerous plants, animals, and fungi, including complex relationships with various species of ant, and have greatly impacted the evolution of plants. Larval mayflies are generally herbivorous; adults have short lifespans and do not eat at all. Most members of the order Orthoptera; for instance, most grasshoppers and katydids are herbivores Butterflies Many beetles of the Scarabaeoidea, including many scarabs, like the goliath and rhinoceros beetles (e.g., the hercules beetle), and all of the stag beetles The jewel beetles (family Buprestidae) Certain ladybugs (family Coccinellidae): The subfamily Epilachninae, comprising 1/6 of all ladybug species, is entirely herbivorous, including members such as the Mexican bean beetle and the bryony ladybird. The leaf beetles (family Chrysomelidae) The weevils (family Curculionidae) Almost all adult bees (clade Anthophila), including mason bees, honeybees, bumblebees, sweat bees, and carpenter bees All true bugs (order Hemiptera) outside of Heteroptera are herbivores, including cicadas, leafhoppers, treehoppers, planthoppers, aphids, scale insects, and whiteflies Most Heteropterans are also herbivorous, including most of the leaf-footed bugs, seed bugs and their relatives, plant bugs, and shield, stink, and burrowing bugs and their relatives
Other invertebrates Most terrestrial isopods (woodlice) are detritivores of plant matter Millipedes, with scarce exceptions, are also detritivores of plant matter Bagheera kiplingi, a jumping spider Caphyra rotundifrons, a crab Garden snails and slugs
Vertebrates
Fish Herbivorous fish play a key role in maintaining healthy ecosystems, especially in tropical reefs, where they promote a balance between corals and macroalgae. Herbivorous fish include: Acanthurus lineatus or lined surgeonfish (also known as blue-banded surgeonfish, blue-lined surgeonfish, clown surgeonfish, pajama tang, striped surgeonfish, and zebra surgeonfish) Acanthurus nigrofuscus, known as the lavender tang, brown tang, or spot-cheeked surgeonfish Zebrasoma scopas, known as the brown tang, two-tone tang, scopas tang or brush-tail tang. The unicornfishes (Nasinae) genus is primarily herbivorous. Most of the nearly 100 species of the parrotfish family are herbivores.Lieske, E., and Myers, R. (1999). Coral Reef Fishes. 2nd edition. Princeton University Press. Grass carp, so named for its diet of aquatic plants. The various genera of pacu are mostly herbivorous. The majority of Loricariidae, including most pleco and Otocinclus species, are predominantly or exclusively herbivorous.
Amphibians Unusually for tetrapods, herbivory is rare among extant adult lissamphibians. There are, however, many larval and a few adult amphibians which take significant plant matter: At least two species of siren (and possibly the entire family) will consume algae, though they are still primarily carnivorous or omnivorousHill, R. L., Mendelson, J. R. & Stabile, J. L. 2015. Direct observation and review of herbivory in Sirenidae (Amphibia: Caudata). Southeastern Naturalist 14, N5-N9. The Indian green frog is mostly herbivorous Xenohyla truncata, the Izecksohn's Brazilian treefrog, is significantly frugivorous The majority of frog tadpoles are primarily herbivorous
Reptiles
Squamates (lizards, snakes, and worm lizards) All snakes and the majority of non-snake squamates (lizards) are carnivorous. However, some degree of herbivory is relatively common among lizards. Perhaps 12% of lizards have diets which are >10% herbivorous. Dedicated herbivory, with plants constituting >90% of the diet, occurs in perhaps ~1% of lizards, though estimates vary. Iguanas (family Iguanidae) are overwhelmingly herbivores; members such as the rhinoceros iguana, marine iguana, green iguana, Lesser Antillean iguana, chuckwallas, desert iguana, and Galápagos land iguana are virtually exclusively herbivorous Members of the family Liolaemidae are herbivores The Panay, Northern Sierra Madre forest, and Gray's monitor lizards are the only three species of herbivorous Varanid Species of the Agamid genus Uromastyx, the spiny-tailed lizards, are herbivores Certain skinks; the Solomon Islands skink is exclusively herbivorous. King's skink is also primarily a herbivore. The extinct Cape Verde giant skink was herbivorous.
Chelonians (turtles/tortoises) Tortoises, consisting of the family Testudinidae, are all almost exclusively herbivorous Adult green sea turtles are herbivorous, uniquely among sea turtles
Dinosaurs (non-avian) Sauropods Ornithischians Marginocephalia Ceratopsians Pachycephalosaurs Thyreophora Stegosaurs Ankylosaurs Ornithopods Hadrosaurs Theropods Therizinosaurs
Birds Although, by some counts, only 2-3% of extant bird species are primarily herbivorous, herbivorous birds are nonetheless incredibly diverse, having evolved independently within at least nine distinct lineages. Herbivorous birds include important pollinators and seed dispersers, as well as both the smallest and largest living birds (the bee hummingbird and the common ostrich, respectively). On islands with little to no mammalian colonization, large herbivorous birds frequently evolved to assume niches typically held by mammals, sometimes attaining enormous sizes; on the Hawaiian Islands, New Zealand, Madagascar, Mauritius, New Caledonia, and Fiji, birds were nearly if not the largest terrestrial herbivores, though the vast majority are now extinct. Birds which are mostly herbivorous as adults will frequently feed their young a far more insectivorous diet, though there are many exceptions.
Palaeognathae Ratites, excluding the kiwis, are often described as omnivorous, and will eat varying quantities of small animals and insects. However, the typical wild diet for non-kiwi ratites is overwhelmingly and sometimes exclusively herbivorous: Ostrich diets can be over 99% herbivorous, though this may vary, but not significantly Rheas: the lesser rhea and greater rhea are essentially 100% herbivorous (though this can drop to 97% for greater rheas in some cases) Emus may be nearly 100% herbivorous in wild habitats, but can also engage in significant insectivory at times The three species of cassowary are virtually exclusively frugivorous, though the dwarf cassowary's diet can be up to 3% insect at times; cassowaries will also consume significant volumes of mushrooms The (recently extinct) moas (order Dinornithiformes) and elephant birds (order Aepyornithiformes) were herbivores Tinamous: although data are scarce, many tinamous are quite omnivorous, and some are primarily insectivores. However, the vast majority of tinamous are primarily herbivorous, sometimes nearly exclusively: Crypturellus species, such as the yellow-legged and Tataupa tinamous, are predominantly frugivorous, with some (largely seasonal) insect consumption Nothura and Nothoprocta species are predominantly granivorous or seed-eating; the Andean tinamou is over 90% herbivorous, while Darwin's nothura is ~95% herbivorous or more, and the ornate tinamou averages nearly 99% Many Tinamus species are overwhelmingly frugivorous, such as the solitary tinamou; the black tinamou has only been observed eating fruits and seeds, but is assumed to consume some insects
Galloanserae Anseriformes: the ducks and their relatives are predominantly herbivorous; although a few species consume primarily animal matter and several are heavily omnivorous, at least a quarter of the 99 species included in one study were 70% herbivorous or more. Herbivorous taxa are varied, including: The screamers, such as the southern screamer and the horned screamer, are totally herbivorous Magpie geese are essentially purely herbivorous The majority of Anatids range from largely to almost exclusively herbivorous (notably excluding the Mergini): Whistling ducks are all nearly 100% herbivorous, including the fulvous, white-faced, and black-bellied whistling ducks Almost all of the Anserinae, including both young and adults: Cape Barren geese are strict herbivores Swans (genus Cygnus) are all 100% herbivorous or very nearly so, including the mute, black, black-necked, tundra, trumpeter, and whooper swans Black geese (genus Branta) are all exclusively herbivorous; examples include the Canada goose, brant, barnacle goose, and nene True geese (genus Anser) are all essentially pure herbivores, such as the greylag, snow, bar-headed, pink-footed, and swan geese Certain Tadornines are virtually purely herbivorous (note that the circumscription of Tadorninae varies): Egyptian geese Orinoco geese