In nature, there are many types of animals that are a danger to others, feed on them or act as dominant. It's not as scary as it seems at first glance - usually in nature everything is balanced in such a way that all kinds, despite the death of individual animals, survive. However, unimpeded invasion of predators on the habitat where they should not lead to catastrophic consequences - are disappearing Species and entire ecosystems, and sometimes even human dwellings are inadequate protection.
Similar to the alien invader, starfish represents the nightmare of sharp needles covered with skin. Usually starfish reach 33 cm in diameter and have a five-rays protruding from the body that are covered with razor-sharp, thorns that protect them from most predators. The stars are powered by coral polyps.
Sea stars have become a problem in its native ecosystem in relation to environmental changes. Thanks to the insatiable appetite and a rapid rate of reproduction, every star in the "herd" can consume up to six m2 of coral reefs in the year, destroying massive portions.
Scientists believe that too rapid increase in the number of starfish called the man provoked changes in the ocean ecosystem, associated primarily with increased nutrient pollution. As a result, some areas have been implemented programs for the destruction of sea stars with the use of lethal toxins.
2. European starling
Starlings were brought to North America by settlers who are nostalgic, apparently under the influence of Shakespeare, which is one of the plays of Eugene Sheffelina described the hero, the self-styled messiah who called each left their homeland to lead a foreign land Bird. 60 starlings so really were brought to America, however, much later, and released to the wild in Central Park in Manhattan.
Starlings quickly spread across the continent from Central America to Alaska: they invaded the city and on the field, destroyed crops and partially or completely destroyed many native birds, including woodpeckers, tits and swallows.
Flocks of starlings threaten aircraft - once killed 62 people because the aircraft was sucked into the engine starling. Despite the large-scale programs to combat them, the number of European starlings in North America is currently about 150 million individuals.
3. Giant Canada Goose
Although Canada does not have a bird, a symbol of serving the country, the vast majority of wildlife enthusiasts have attributed to this role, the Canada Goose, as birds of this species in Canada, more than all the rest. Nevertheless, Canada - quite a big country, it was enough to place several subspecies of geese with different habitats and lifestyles.
Canadian Geese are the originators of the progressive destruction of the shoreline along the mouth of the Gulf of Georgia. This area is of great importance because staying here many species of migratory birds, in addition, this is the main habitat of salmon - food fish, endangered.
Neil K. Doe, who studies wildlife, conducted field research to study the state of the mouth of the bay, and the published results showing that the geese are destroying the natural habitat of many animals and are the cause of human food chain.
4. Dark tiger python
The majority of invasive species are small animals, but dark tiger pythons - huge and potentially deadly giants. They first appeared in the Everglades National Park (Florida), the world-famous swamp region. This monster, brought to America by the conquistadors - one of the largest snakes on the planet, he grows up to five meters in length and weighs about 90 kg.
Now the number of snakes in the Everglades several thousand individuals, and it is more than their original habitat in South Asia. Giant pythons, which have powerful jaws and sharp teeth, threatening to destroy the ecosystem of the wetland area as quickly decimating native species, including the usually invincible American alligators.
State authorities say the destruction of nature protection of snakes in this region a priority, but so far all precautions have been ineffective.
5. Aga (cane toad)
Instead, to exterminate the bugs and leave it at that, AGI bred in the vast territory, leading to the decline of the native fauna. They are hunted, including prey on lizards, mammals, marsupials and singing birds, and even ruin the laying of eggs of sea-eating crocodiles.
As is the case with other Invasive Species, the number of cane toads remain artificially high in the new conditions in the absence of predators that could eat them and are resistant to toxins.
The proposal to reduce the population of toads by viruses has raised fears - in the future, this measure may cause a chain reaction and cause irreparable damage to the local wildlife. By coincidence, a natural toxin toad is currently being used to kill tadpoles.
6. Brown boyga
If predatory invasive species is on the island, local species, as a rule, do not have the ability to cope with the threat that had never before encountered. Coupled with the lack of predators higher up the food chain, it can cause the disappearance of native species.
When brown boygi arrived on the island of Guam after World War II, probably as stowaways in cargo holds of ships, it caused the biggest environmental disaster caused by the introduction.
Poisonous snakes destroyed most vertebrates, originally found in the forests of the island, they also bite humans, and their bites are very painful. In addition, boygi caused frequent interruptions of electricity, since invaded the human settlements.
In a secure environment boygi grow to three meters in length due to abnormally high amount of food. To control the number of reptiles used the introduction of toxins in the dead mice that snakes like to eat.
7. Plague Rat and Mouse
Swim across oceans in ships not only people but also their mortal enemies - rats and mice. Sometimes are vectors of disease, rodents become a death sentence for all the populations of sea birds when planted together with people on the coast: they eat the eggs and young, and sometimes even adult petrels, puffins and other wetland birds, unable to defend their nests from mammalian predators.
The presence of invasive rats contributes to global extinction of marine birds, for example, rats consume up to 25 thousand petrel chicks per year. No less dangerous invasive house mouse, harming species, and so endangered, for example, tristanskim albatross: mice are not only ruining their clutches, but also eat chicks alive.
8. Domestic cat
The catastrophic consequences is the presence of cats on the islands known unprecedented case when the cat one person has caused extinction of a species of bird in New Zealand - Stephan bush wren.
On many islands and continents invasive cats have caused population declines of birds and small mammals. But there's a downside: some scientists believe that cats can help the people in the control populations of small predators such as rats.
Most often, the main invasive species on the planet environmentalists call people, but we rarely present in the role of monkeys. However, cynomolgus included the International Union for Conservation of Nature's list of 100 most dangerous invasive species. Cynomolgus monkeys - is carnivorous primates, invading a number of islands in an unnatural environment for them thanks to the assistance of man.
Like many terrestrial predators, cynomolgus monkeys, which have, in addition, the rudiments of intelligence, threatened breeding bird and, according to some experts, may be responsible for the rapid extinction of the already endangered species.