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148

invasive species

OLogy Series
biology
card
148

invasive species

OLogy Series
biology

An invasive species is a living thing that moves into a new region. Species often become "invasive" as a result of human activities. Invasive species can threaten local plants and animals by competing with them for resources. Sometimes this can lead to the extinction of native species. Once invasive species become established, they can greatly change a habitat.

Attack of the Giant Snails
The giant African snail was introduced to Hawaii in the 1930s. These snails reproduce in a short amount of time and can destroy farmers' crops, so they are a serious agricultural pest. The rosy wolfsnail was then introduced to control this pest, but it was also a predator of other native snails and drove some species to extinction on the islands. If that wasn't bad enough, in 1966, a boy returning from Hawaii smuggled three giant snails to Miami. His grandmother released them into her garden, where they reproduced and spread. Soon, the problem became so severe that the Florida Division of Plant Industry was called in to deal with the snails. Within 42 city blocks, more than 17,000 snails were found. To remove them, the FDPI picked up the snails by hand and with chemical bait. It took more than 9 years and more than one million dollars to get rid of the giant snails in Florida.

The Cat That Invaded Stephens Island
In 1894, a lighthouse keeper and his cat lived on a little island off the coast of New Zealand called Stephens Island. The lighthouse keeper's cat loved to catch birds -- so much so that one day it brought back 17 dead birds! The lighthouse keeper sent one of the birds to a museum for identification. It turned out that the bird was a species of wren that had never been seen before. Ornithologists decided to name the bird the Stephens Island wren. While this exciting discovery was being made, the lighthouse keeper's cat continued to bring back more birds. The Stephens Island wrens could not fly, making them very easy for the cat to catch. Eventually, the cat killed so many birds that it caused the extinction of the entire species of the Stephens Island wren. Cats, dogs, ferrets, reptiles, and many other pets can be harmful to a habitat and local species if they are not properly controlled. If you have pets, look after them responsibly and keep control of them. This will help protect your pets and biodiversity, too.

Today there are over 200 million European starlings living in the United States because they:

flew here from Europe

escaped from pet stores

were released by people

Are you right?

Correct!

In the late 1890s, a group of people wanted to introduce birds mentioned in Shakespearean literature to the United States. They brought 100 starlings from Europe and released them in New York. These avian invaders take over nesting cavities and leave less room for native birds.

How did zebra mussels travel from Europe to the United States?

swimming

flying on airplanes

hitching rides on cargo ships

Are you right?

Correct!

In the 1980s, a few zebra mussels hitched rides on cargo ships traveling from Europe to the United States. These mussels took over, and made it difficult for native mussel species to survive.

invasive species
What: a plant or animal that is introduced into a different habitat by people on purpose or accidentally
How: species are introduced on ships, planes, suitcases, tents, cars, or are deliberately moved by people
Significance: can change existing habitats, push out or eat native wildlife, destroy plants, spread diseases, and cause many other problems

Image credits: European starling, courtesy of Dr. W. Dan Sudia, FLMNH Photo Gallery of Southeastern U.S. Birds African land snail, courtesy of Duane Meier, Honolulu Zoo, Wicked Willy photo gallery cat, courtesy of AMNH.