Not all invasive species are considered harmful. In many ways, these species can help the environment. The name "Invasive" often suggests that these species destroy the ecosystems rather than help it. But for some species they do help. There are few invasive organisms that are actually beneficial to the environment. For example in California native butterflies feed on non-native plants. In Puerto Rico, alien trees help restore abandoned pastures to a condition suitable for native plants. Even mussels helps filter toxins from lakes.
Most non-native species are harmless or even helpful. honeybees, earthworms, and grains are actually imports from Europe. Most species arrive from somewhere else, so the definition of 'native' depends on where the species are being traced from. Using this explanation even humans could be considered an invasive species. Every living organism originated from somewhere, and that place is different from where they are now.
Factors like animal migrations and even climate problems such as global warming contributes to the reason for why species move to different areas. Animals migrate for many reasons. They could be searching for a new home or migration is natural and is apart of what that species does to survive. Either way, they end up in new environments which can have an increase in biodiversity. Also global warming is a factor that calls for species to move into new areas. Species, mainly animals, cannot live in certain weather conditions. Animals such as penguins and polar bears, whose bodies are made to live in cold weather areas, have trouble surviving in warm weather area because there are more predators and competition.
Overall, most people believe invasive species are harmful to the environment. An invasive species is a plant, fungus, or animal species that is not native to a specific location, and which has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health. As mentioned in the definition, invasive species are not just animals, but any kind of living organism. They are also considered one of the leading threats to native wildlife. About 42% of threatened or endangered species are at risk primarily due to invasive species. Not only animals, but humans and our health as well as economics are also at risk from invasive species. Invasive species can bring in diseases. Because these organisms are from different areas were there are different living conditions, they travel to other environments were this diseases is not common. Species like mosquitoes and raccoons carry malaria and rabies. These animals can easily travel to different habitats and spread these diseased to different organisms.
Preventing invasive species is a hard task. These organisms can take out native species and cause a decline in water quality. Because of this, boating and fishing becomes more difficult. Altogether, invasive species can impact ecosystems negatively in several ways. They can also reduce habitats, weaken recreational activities, have an negative effect on biodiversity, reduce productivity and displace native species.