This article is about anatomically and physiologically adapted diets to plants. For the japanese social phenomenon, see Herbivore men
organism that eats largely or entirely implant material
deer and two fawns feeding on foliage sawfly larva feeding on a leaf Tracks made by mundane gastropods with their radulas, scraping green alga from a surface inside a greenhouse

A herbivore is an animal anatomically and physiologically adapted to eating establish material, for example foliation or marine alga, for the main component of its diet. As a consequence of their implant diet, herbivorous animals typically have mouthparts adapted to rasping or grinding. Horses and other herbivores have wide bland teeth that are adapted to grinding grass, tree bark, and other bully plant substantial. A bombastic percentage of herbivores have mutualistic gut plant that help them digest plant matter, which is more unmanageable to digest than animal prey. [ 1 ] This vegetation is made up of cellulose -digesting protozoans or bacteria. [ 2 ]


herbivore is the anglicise imprint of a mod Latin neologism, herbivora, cited in Charles Lyell ‘s 1830 Principles of Geology. [ 3 ] Richard Owen employed the anglicise condition in an 1854 work on dodo teeth and skeletons. [ 3 ] Herbivora is derived from Latin herba ‘small plant, herb ‘ [ 4 ] and vora, from vorare ‘to consume, devour ‘. [ 5 ]

definition and relate terms

Herbivory is a phase of consumption in which an organism chiefly eats autophyte [ 6 ] such as plants, alga and photosynthesizing bacteria. More by and large, organisms that feed on autophyte in general are known as primary consumers. Herbivory is normally limited to animals that eat plants. Fungi, bacteria, and protists that feed on surviving plants are normally termed plant pathogens ( plant diseases ), while fungi and microbes that feed on dead plants are described as saprotrophs. Flowering plants that obtain nutrition from other exist plants are normally termed parasitic plants. There is, however, no single exclusive and definitive ecological classification of consumption patterns ; each casebook has its own variations on the theme. [ 7 ] [ 8 ] [ 9 ]

evolution of herbivory

fossil Viburnum lesquereuxii leaf with evidence of insect herbivory; Dakota Sandstone ( leaf with attest of insect herbivory ; Dakota Sandstone ( Cretaceous ) of Ellsworth County, Kansas. Scale bar is 10 millimeter. The understand of herbivory in geological prison term comes from three sources : fossilized plants, which may preserve tell of defense ( such as spines ), or herbivory-related damage ; the observation of plant debris in fossilize animal faeces ; and the structure of herbivore mouthparts. [ 10 ] Although herbivory was long thought to be a Mesozoic phenomenon, fossils have shown that plants were being consumed by arthropods within less than 20 million years after the inaugural land plants evolved. [ 11 ] Insects fed on the spores of early devonian plants, and the Rhynie chert besides provides attest that organisms fed on plants using a “ pierce and fellate ” proficiency. [ 10 ] During the next 75 million years [ citation needed ], plants evolved a range of more complex organs, such as roots and seeds. There is no attest of any organism being fed upon until the middle-late Mississippian ,. There was a gap of 50 to 100 million years between the time each organ evolved and the clock organisms evolved to feed upon them ; this may be due to the low levels of oxygen during this period, which may have suppressed evolution. [ 11 ] Further than their arthropod status, the identity of these early herbivores is uncertain. [ 11 ] Hole feed and skeletonization are recorded in the early permian, with surface fluid feeding evolving by the end of that period. [ 10 ] Herbivory among four-limbed mundane vertebrates, the tetrapods, developed in the Late Carboniferous ( 307–299 million years ago ). [ 12 ] early tetrapods were large amphibious piscivores. While amphibians continued to feed on fish and insects, some reptiles began exploring two new food types, tetrapods ( carnivory ) and plants ( herbivory ). The entire dinosaur rate ornithischia was composed of herbivorous dinosaurs. [ 12 ] Carnivory was a natural passage from insectivory for medium and big tetrapods, requiring minimal adaptation. In contrast, a complex jell of adaptations was necessary for feeding on highly fibrous plant materials. [ 12 ] Arthropods evolved herbivory in four phases, changing their approach to it in response to changing plant communities. [ 13 ] Tetrapod herbivores made their first gear appearance in the fossil record of their yack near the Permio-Carboniferous limit, approximately 300 million years ago. The earliest evidence of their herbivory has been attributed to dental blockage, the process in which tooth from the upper jaw come in contact with teeth in the lower jaw is present. The evolution of alveolar consonant occluded front led to a drastic increase in implant food work and provides testify about feeding strategies based on tooth wear patterns. examination of phylogenetic frameworks of tooth and call on the carpet morphologes has revealed that alveolar consonant blockage developed independently in respective lineages tetrapod herbivores. This suggests that development and spread occurred simultaneously within respective lineages. [ 14 ]

food chain

Leaf miners feed on leaf tissue between the epidermal layers, leaving visible trails Herbivores form an significant link in the food chain because they consume plants to digest the carbohydrates photosynthetically produced by a plant. Carnivores in act consume herbivores for the lapp reason, while omnivores can obtain their nutrients from either plants or animals. Due to a herbivore ‘s ability to survive entirely on tough and fibrous implant matter, they are termed the basal consumers in the food cycle ( chain ). Herbivory, carnivory, and omnivory can be regarded as special cases of consumer–resource interactions. [ 15 ]

Feeding strategies

Two herbivore feed strategies are grazing ( e.g. cows ) and browsing ( e.g. elk ). For a sublunar mammal to be called a grazer, at least 90 % of the forage has to be grass, and for a browser at least 90 % tree leaves and twigs. An intermediate feed strategy is called “ mixed-feeding ”. [ 16 ] In their daily need to take up energy from scrounge, herbivores of different body mass may be selective in choosing their food. [ 17 ] “ selective ” means that herbivores may choose their eatage source depending on, for example, season or food handiness, but besides that they may choose high quality ( and consequently highly alimentary ) foraging before lower quality. The latter particularly is determined by the body mass of the herbivore, with small herbivores selecting for high-quality forage, and with increasing body batch animals are less selective. [ 17 ] several theories attempt to explain and quantify the relationship between animals and their food, such as Kleiber ‘s law, Holling ‘s harrow equation and the marginal value theorem ( see below ). Kleiber ‘s law describes the relationship between an animal ‘s size and its fertilize scheme, saying that larger animals need to eat less food per whole weight than smaller animals. [ 18 ] Kleiber ‘s law states that the metabolic rate ( q0 ) of an animal is the mass of the animal ( M ) raised to the 3/4 baron : q0=M3/4 therefore, the mass of the animal increases at a faster rate than the metabolic rate. [ 19 ] Herbivores employ numerous types of feeding strategies. many herbivores do not fall into one specific feeding strategy, but use several strategies and eat a assortment of plant parts .
optimum Foraging Theory is a mannequin for predicting animal behavior while looking for food or other resources, such as shelter or water. This exemplar assesses both individual motion, such as animal behavior while looking for food, and distribution within a habitat, such as dynamics at the population and community level. For case, the model would be used to look at the browsing demeanor of a deer while looking for food, arsenic well as that deer ‘s specific location and drift within the forested habitat and its interaction with other deer while in that habitat. [ 20 ] This exemplary has been criticized as circular and untestable. Critics have pointed out that its proponents use examples that fit the theory, but do not use the model when it does not fit the reality. [ 21 ] [ 22 ] other critics point out that animals do not have the ability to assess and maximize their potential gains, therefore the optimum scrounge theory is irrelevant and derived to explain trends that do not exist in nature. [ 23 ] [ 24 ] Holling ‘s harrow equation models the efficiency at which predators consume prey. The mannequin predicts that as the issue of prey increases, the sum of time predators spend handling prey besides increases, and consequently the efficiency of the marauder decreases. [ 25 ] [ page needed ] In 1959, S. Holling proposed an equation to model the rate of render for an optimum diet : rate ( R ) =Energy gained in foraging ( Ef ) / ( time searching ( Ts ) + fourth dimension manage ( Th ) )
R = E farad / ( T s + T henry ) { \displaystyle R=Ef/ ( Ts+Th ) } {\displaystyle R=Ef/(Ts+Th)}
Where s=cost of search per unit clock time f=rate of run into with items, h=handling prison term, e=energy gained per find
In effect, this would indicate that a herbivore in a dense afforest would spend more fourth dimension cover ( eating ) the vegetation because there was so a lot vegetation around than a herbivore in a sparse forest, who could easily browse through the forest vegetation. According to the Holling ‘s magnetic disk equality, a herbivore in the sparse forest would be more efficient at eating than the herbivore in the dense afforest. The bare value theorem describes the symmetry between eating all the food in a plot for immediate energy, or moving to a new patch and leaving the plants in the first patch to regenerate for future use. The theory predicts that lacking complicating factors, an animal should leave a resource patch when the rate of wages ( sum of food ) falls below the average rate of bribe for the stallion area. [ 26 ] According to this hypothesis, an animal should move to a new piece of food when the patch they are presently feeding on requires more energy to obtain food than an average patch. Within this hypothesis, two subsequent parameters emerge, the Giving Up Density ( GUD ) and the Giving Up Time ( GUT ). The Giving Up Density ( GUD ) quantifies the amount of food that remains in a patch when a forager moves to a new patch. [ 27 ] The Giving Up Time ( GUT ) is used when an animal endlessly assesses the patch quality. [ 28 ]

Plant-herbivore interactions

Interactions between plants and herbivores can play a prevailing function in ecosystem dynamics such community structure and functional processes. [ 29 ] [ 30 ] Plant diverseness and distribution is often driven by herbivory, and it is likely that trade-offs between implant competitiveness and defensiveness, and between colonization and mortality allow for coexistence between species in the presence of herbivores. [ 31 ] [ 32 ] [ 33 ] [ 34 ] however, the effects of herbivory on plant diverseness and affluence is varying. For example, increased abundance of herbivores such as deer decrease plant diverseness and species profusion, [ 35 ] while other big mammal herbivores like bison master dominant species which allows other species to flourish. [ 36 ] Plant-herbivore interactions can besides operate so that plant communities mediate herbivore communities. [ 37 ] Plant communities that are more divers typically sustain greater herbivore richness by providing a greater and more divers specify of resources. [ 38 ] Coevolution and phylogenetic correlation between herbivores and plants are important aspects of the influence of herbivore and plant interactions on communities and ecosystem functioning, specially in respect to herbivorous insects. [ 30 ] [ 37 ] [ 39 ] This is apparent in the adaptations plants develop to tolerate and/or defend from worm herbivory and the responses of herbivores to overcome these adaptations. The evolution of antagonistic and mutualistic plant-herbivore interactions are not mutually single and may co-occur. [ 40 ] Plant evolution has been found to facilitate the colonization and community assembly of herbivores, and there is evidence of phylogenetic linkage between plant beta diverseness and phylogenetic beta diverseness of insect clades such as butterflies. [ 37 ] These types of eco-evolutionary feedbacks between plants and herbivores are probably the main drive effect behind plant and herbivore diverseness. [ 37 ] [ 41 ] Abiotic factors such as climate and biogeographic features besides impact plant-herbivore communities and interactions. For exercise, in moderate fresh water wetlands herbivorous waterfowl communities change according to season, with species that eat above-ground vegetation being abundant during summer, and species that forage below-ground being introduce in winter months. [ 29 ] [ 34 ] These seasonal worker herbivore communities differ in both their hookup and functions within the wetland ecosystem. [ 34 ] such differences in herbivore modalities can potentially lead to trade-offs that determine species traits and may lead to linear effects on residential district writing and ecosystem serve. [ 29 ] [ 34 ] Seasonal changes and environmental gradients such as elevation and latitude much affect the palatability of plants which in change state influences herbivore community assemblages and frailty versa. [ 30 ] [ 42 ] Examples include a decrease in abundance of leaf-chewing larva in the fall when hardwood flick palatability decreases ascribable to increased tannin levels which results in a decline of arthropod species richness, [ 43 ] and increased palatability of plant communities at higher elevations where grasshoppers abundances are lower. [ 30 ] climatic stressors such as ocean acidification can lead to responses in plant-herbivore interactions in relation back to palatability angstrom well. [ 44 ]

Herbivore offense

The countless defenses displayed by plants means that their herbivores need a assortment of skills to overcome these defenses and obtain food. These give up herbivores to increase their feed and use of a host plant. Herbivores have three primary strategies for dealing with plant defenses : choice, herbivore modification, and plant change. Feeding choice involves which plants a herbivore chooses to consume. It has been suggested that many herbivores feed on a variety show of plants to balance their alimentary uptake and to avoid consuming excessively much of any one type of defensive chemical. This involves a tradeoff however, between foraging on many implant species to avoid toxins or specializing on one type of plant that can be detoxified. [ 45 ]

Herbivore change is when versatile adaptations to consistency or digestive systems of the herbivore allow them to overcome implant defenses. This might include detoxifying secondary metabolites, [ 46 ] sequestering toxins unaltered, [ 47 ] or avoiding toxins, such as through the production of large amounts of saliva to reduce effectiveness of defenses. Herbivores may besides utilize symbionts to evade plant defenses. For example, some aphids use bacteria in their intestine to provide essential amino acids lacking in their blackjack diet. [ 48 ] establish modification occurs when herbivores manipulate their plant raven to increase feed. For example, some caterpillars roll leaves to reduce the potency of plant defenses activated by sunlight. [ 49 ]

plant defense

A plant department of defense is a trait that increases implant fitness when faced with herbivory. This is measured relative to another implant that lacks the defensive trait. Plant defenses increase survival and/or reproduction ( seaworthiness ) of plants under pressure of depredation from herbivores. [ citation needed ] defense can be divided into two main categories, tolerance and resistance. tolerance is the ability of a plant to withstand damage without a decrease in fitness. [ 50 ] This can occur by diverting herbivory to non-essential plant parts, resource allocation, compensatory emergence, or by rapid regrowth and recovery from herbivory. [ 51 ] Resistance refers to the ability of a plant to reduce the measure of damage it receives from herbivores. [ 50 ] This can occur via avoidance in space or time, [ 52 ] physical defenses, or chemical defenses. Defenses can either be constituent, always present in the plant, or induced, produced or translocated by the plant following price or stress. [ 53 ] physical, or mechanical, defenses are barriers or structures designed to deter herbivores or reduce inhalation rates, lowering overall herbivory. Thorns such as those found on roses or acacia trees are one exemplar, as are the spines on a cactus. Smaller hairs known as trichomes may cover leaves or stems and are particularly effective against invertebrate herbivores. [ 54 ] In summation, some plants have waxes or resins that alter their texture, making them difficult to eat. besides the incorporation of silica into cell walls is analogous to that of the character of lignin in that it is a compression-resistant morphologic part of cellular telephone walls ; so that plants with their cell walls impregnated with silica are thereby afforded a measuring stick of protection against herbivory. [ 55 ] Chemical defenses are secondary metabolites produced by the plant that deter herbivory. There are a wide kind of these in nature and a single plant can have hundreds of unlike chemical defenses. Chemical defenses can be divided into two chief groups, carbon-based defenses and nitrogen-based defenses. [ citation needed ]

  1. Carbon-based defenses include terpenes and phenolics. Terpenes are derived from 5-carbon isoprene units and comprise essential oils, carotenoids, resins, and latex. They can have several functions that disrupt herbivores such as inhibiting adenosine triphosphate (ATP) formation, molting hormones, or the nervous system.[56] Phenolics combine an aromatic carbon ring with a hydroxyl group. There are several different phenolics such as lignins, which are found in cell walls and are very indigestible except for specialized microorganisms; tannins, which have a bitter taste and bind to proteins making them indigestible; and furanocumerins, which produce free radicals disrupting DNA, protein, and lipids, and can cause skin irritation.
  2. Nitrogen-based defenses are synthesized from amino acids and primarily come in the form of alkaloids and cyanogens. Alkaloids include commonly recognized substances such as caffeine, nicotine, and morphine. These compounds are often bitter and can inhibit DNA or RNA synthesis or block nervous system signal transmission. Cyanogens get their name from the cyanide stored within their tissues. This is released when the plant is damaged and inhibits cellular respiration and electron transport.[ quotation needed]

Plants have besides changed features that enhance the probability of attracting natural enemies to herbivores. Some emit semiochemicals, odors that attract natural enemies, while others provide food and caparison to maintain the natural enemies ‘ presence, e.g. ants that reduce herbivory. [ 57 ] A given plant species frequently has many types of defensive mechanisms, mechanical or chemical, constituent or induced, which allow it to escape from herbivores. [ citation needed ]

Predator–Prey Theory

According to the theory of marauder –prey interactions, the kinship between herbivores and plants is cyclic. [ 58 ] When raven ( plants ) are numerous their predators ( herbivores ) increase in numbers, reducing the prey population, which in go causes predator act to decline. [ 59 ] The prey population finally recovers, starting a newfangled bicycle. This suggests that the population of the herbivore fluctuates around the carrying capacity of the food source, in this lawsuit, the plant. respective factors play into these fluctuate populations and help stabilize predator-prey dynamics. For example, spatial heterogeneity is maintained, which means there will always be pockets of plants not found by herbivores. This stabilizing moral force plays an specially important role for specialist herbivores that feed on one species of plant and prevents these specialists from wiping out their food informant. [ 60 ] Prey defenses besides help stabilize predator-prey dynamics, and for more information on these relationships see the section on Plant Defenses. Eating a second raven type helps herbivores ‘ populations stabilize. [ 61 ] Alternating between two or more plant types provides population stability for the herbivore, while the populations of the plants oscillate. [ 62 ] This plays an significant character for renaissance man herbivores that eat a variety show of plants. Keystone herbivores keep vegetation populations in check and allow for a greater diversity of both herbivores and plants. [ 61 ] When an encroaching herbivore or plant enters the system, the balance is thrown away and the diverseness can collapse to a monotaxon system. [ 61 ] The back and forth relationship of plant defense and herbivore umbrage drives coevolution between plants and herbivores, resulting in a “ coevolutionary arms race ”. [ 46 ] [ 63 ] The scat and radiation sickness mechanisms for coevolution, presents the idea that adaptations in herbivores and their host plants, has been the driving force behind speciation. [ 64 ] [ 65 ]


While a lot of the interaction of herbivory and plant defense is minus, with one individual reducing the fitness of the early, some is beneficial. This beneficial herbivory takes the class of mutualisms in which both partners benefit in some manner from the interaction. Seed dispersion by herbivores and pollination are two forms of mutualistic herbivory in which the herbivore receives a food resource and the plant is aided in reproduction. [ 66 ] Plants can besides be indirectly affected by herbivores through nutrient recycle, with plants benefiting from herbivores when nutrients are recycled very efficiently. [ 40 ] Another mannequin of plant-herbivore symbiosis is forcible changes to the environment and/or plant residential district structure by herbivores which serve as ecosystem engineers, such as wallowing by bison. [ 67 ] Swans form a common relationship with the plant species that they forage by digging and disturbing the sediment which removes competing plants and subsequently allows colonization of early plant species. [ 29 ] [ 34 ]


Trophic Cascades and Environmental Degradation

When herbivores are affected by trophic cascades, plant communities can be indirectly affected. [ 68 ] Often these effects are felt when predator populations decline and herbivore populations are no long limited, which leads to intense herbivore foraging which can suppress establish communities. [ 69 ] With the size of herbivores having an affect on the total of energy intake that is needed, larger herbivores need to forage on higher quality or more plants to gain the optimum come of nutrients and energy compared to smaller herbivores. [ 70 ] Environmental abasement from white-tailed deer ( Odocoileus virginianus ) in the US entirely has the electric potential to both change vegetative communities [ 71 ] through over-browsing and price forest restoration projects upwards of $ 750 million annually. Another example of a trophic cascade involved plant-herbivore interactions are coral reef ecosystems. herbivorous fish and nautical animals are authoritative algae and seaweed grazers, and in the absence of plant-eating fish, corals are outcompeted and seaweeds deprive corals of sunlight. [ 72 ]

economic Impacts

agricultural crop damage by the lapp species totals approximately $ 100 million every year. Insect snip damages besides contribute largely to annual crop losses in the U.S. [ 73 ] Herbivores besides affect economics through the gross generated by hunting and ecotourism. For exercise, the hound of herbivorous game species such as white-tailed deer, wood rabbit rabbits, antelope, and wapiti in the U.S. contributes greatly to the billion-dollar annually, hunting industry. [ citation needed ] Ecotourism is a major generator of gross, particularly in Africa, where many bombastic mammalian herbivores such as elephants, zebras, and giraffes help to bring in the equivalent of millions of US dollars to diverse nations annually. [ citation needed ]

See besides


further read