The worst invasive species ever?

http://www.environmentalgraffiti.com/offbeat-news/the-5-worst-invasive-species-in-the-world/463

Throughout the years, many different type on introduced species have impacted the world and native species in one way or another. These few species are thought to be some of the worst introduced species yet.

Feral pigs are considered to be a bad introduced species. Although they were introduced through farming, many escaped. These pigs would tear through large chunks of land in order to find food, which would in turn negatively impact plant species, for their roots would be damaged and the plant would die, which would also harm species that rely on the plants for nourishment. These pigs would also consume cropland, causing millions of dollars of damage every year. In specific places, they would eat the native species eggs, causing their numbers to decrease. A location of example is Santiago Island, where sea turtle numbers were drastically reduced because of the eggs being consumed by the pigs.

Zebra mussles are also thought to be one of the worst introduced species. The zebra mussel, which is native to western Asia, was introduced into Europe during the 1700's. They were then introduced into North America by a European ship that accidentally released them into the Great Lakes. They caused millions of dollars in damage by colonizing water intake pipes which would then become clogged. There is also competition for food between them, and the native species.

However, one of the worst introduced species is the European rabbit. These rabbits were introduced by choice, when a hunter names Thomas Austin released twenty-four of the animals in order to have variety in the animals he would shoot. While other farmers also released rabbits, it is thought that Austin was responsible for the infestation. This human impact caused a horrible infestation that not only caused agricultural damage, but also helped contribute by nurturing many other non-native species such as foxes, or feral cats, which further damaged Australia's ecosystem.

Response: I never knew the damage caused by these species! it is truly amazing that these animals were very close in causing the extinction of others. It also surprised me that people released one by choice! I cannot believe that people would stoop so low just to get a thrill.

QUESTIONS:

1. Who released the European Rabbit?

2. Why are Zebra Mussels a threat?

3. What happened on Santiago Island?

4. How many European rabbits were released?