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Keystone species
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 What is a keystone species?A keystone species is a species that has a disproportionate effect on its environment relative to its abundance. Such an organism plays a role in its ecosystem that is analogous to the role of a keystone in an arch. While the keystone feels the least pressure of any of the stones in an arch, the arch still collapses without it. Similarly, an ecosystem may experience a dramatic shift if a keystone species is removed, even though that species was a small part of the ecosystem by measures of biomass or productivity. (source: Wikipedia.org) Often these species are not protected as they may not be as charismatic or of as much interest as some animals, also not all the keystone species have been identified as it is difficult to determine which they are until removal and subsequent collapse of a community. Many species of sea star are examples of this. Examples of keystone species •Killer Whale (Orcinus orca) * •Prairie dog(Cynomys parvidens) •European Beaver (Castor fiber) •Flying Fox (Pteropus vampyrus) •Grizzly Bear (Ursus arctos) •gopher tortoise (Gopherus polyphemus) As recently as May 2006 an outbreak of Crown-of-Thorns Starfish was discovered feeding off the coral of the Great Barrier reef. These high numbers may be due to the removal of the Triton whelk for the sale of its shells to tourists. Why is a whale a keystone species? Most species of whale take the place at the top of the food web / chain and therefore are responsible for keeping the numbers of their prey down as they have consume such large numbers of their prey. If the numbers of the whales declined they would be less limiting on population numbers of their prey thus creating a population explosion of the prey. Consumption of food by the whales prey would increase with population increases until a point is reach where food is no longer available, in a couple of generations the whole ecosystem could collapse. The time taken for an ecosystem to recover is much longer than it takes to be destroyed. Keystone species can occur at any point within a food chain, the strong reliance the whales have on the krill means that krill are also considered to be keystone species even though take the place near the bottom of the food chain. References Save the Prairie Dogs Grinning Planet Explanation of keystone species Monga Bay Article on keystone species WWF Explanation of keystone species Ecology and Society The link between functional groups and keystone species Wikipedia Definition of keystone species Field Trip Earth Elephants as keystone species WDCS 6 key species of whales under protection Living oceans foundation Crown of thorns starfish out breaks |
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