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Herbivory is of extreme ecological importance and prevalence among insects.Perhaps one third (or 500,000) of all described species are herbivores. [4] 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.
According to the theory of predator–prey interactions, the relationship between herbivores and plants is cyclic. [62] When prey (plants) are numerous their predators (herbivores) increase in numbers, reducing the prey population, which in turn causes predator number to decline. [62] The prey population eventually recovers, starting a new cycle.
Monophagous species (animals that eat plants from a single genus) must produce specialized enzymes to detoxify their food, or develop specialized structures to deal with sequestered chemicals. Polyphagous species (animals that eat plants from many different families), on the other hand, produce more detoxifying enzymes (specifically MFO) to ...
In contrast with the Arctic tundra, the Antarctic tundra lacks a large mammal fauna, mostly due to its physical isolation from the other continents. Sea mammals and sea birds, including seals and penguins, inhabit areas near the shore, and some small mammals, like rabbits and cats, have been introduced by humans to some of the subantarctic islands.
At higher altitudes, the terrain is arctic tundra. Svalbard has permafrost and tundra, with both low, middle and high Arctic vegetation. 165 species of plants have been found on the archipelago. [9] Only those areas which defrost in the summer have vegetation cover and this accounts for about 10% of the island group.
An example is the koala, because it feeds only on eucalyptus leaves. Primary consumers that feed on many kinds of plants are called generalists. Secondary consumers are small/medium-sized carnivores that prey on herbivorous animals. Omnivores, which feed on both plants and animals, can be considered as being both primary and secondary consumers.
These complex interactions between plants, animals and abiotic factors in the tundra are held together by the permafrost layer, located 450 metres (1,480 ft) under the soil. [3] However climate change is causing this crucial layer of frozen soil to melt. As a result, tundra communities are becoming unstable and basic processes are breaking down.
The snowy owl (Bubo scandiacus), [4] also known as the polar owl, the white owl and the Arctic owl, [5] is a large, white owl of the true owl family. [6] Snowy owls are native to the Arctic regions of both North America and the Palearctic, breeding mostly on the tundra. [2]