Invasive animals have a long tradition of negative effects. When an animal, fish, insect, or plant is accidentally or purposefully removed from its natural habitat and placed in a new one, it is less likely to have natural predators.

Some invasive species, especially prolific breeders, thrive when they have little to hold their population in check. They have the ability to kill native plants, consume native animal species, and transmit disease, disrupting the fragile equilibrium of organisms that provide food, shelter, and a check on each other's growth. Extinctions have become common.

Invasive species affect biodiversity in a variety of ways. There may be no natural predators or controls when a new and destructive animal is introduced into an ecosystem.

Preying on native species, outcompeting native species for food or other resources, causing or carrying disease, and stopping native species from reproducing or destroying native species' young are all immediate threats posed by invasive species.

Related Article: Growth of Damaging and Invasive Species Linked To Pet Trade

Here are 5 of the world's most destructive invasive species:

Cane Toad

Cane Toad
(Photo : Wikimedia Commons)

To combat crop pests, cane toads were introduced to Australia. 

Toxic ooze is produced by these toads as a defensive mechanism. Predators in their natural environment are resistant to the poisonous ooze, but predators in other environments are not. Many species who try to consume a cane toad end up dying as a result. Cane toad colonies in non-native environments have increased due to a lack of natural predators, and they are wreaking havoc on native animal and plant ecosystems.

Small Indian Mongoose

Indian Mongoose
(Photo : Wikimedia Commons)

Since small Indian mongooses are dangerous predators, they were initially taken along to many foreign lands to get rid of rats and snakes. The bar-winged rail (now extinct), Jamaica petrel (critically endangered and probably extinct), hawksbill turtles (critically endangered), pink pigeon (endangered), Amami rabbit (endangered), and many other birds, rodents, and mammals have all suffered as a result of them. Rabies and other human ailments are also carried by mongooses.

Asian Carp

Asian Carp
(Photo : Wikimedia Commons)

Bighead carp, black carp, grass carp, and silver carp are the four invasive species known as "Asian carp" in the United States. They were introduced into the United States in the 1970s to help maintain aquatic farms safe, manage weeds in canal systems, and aid sewage treatment. They fled into the Mississippi River delta, where they gorged themselves on the bottom of the marine food chain, with certain animals consuming up to 100% of their body weight daily. Although spreading into new rivers, they have been outbreeding native animals and driving them over their own habitat. Silver carp have been viewed as a threat to boaters and anglers due to their unsettling habit of jumping out of the water.

Burmese Python

Burmese Python
(Photo : Wikimedia Commons)

Everglades National Park employees encountered Florida's first known python in 1979, most likely a Burmese python. By the year 2000, Florida had received records of existing Burmese python populations. These snakes, which can reach a length of 20 feet or more, were brought to Florida as exotic pets.

Many owners, however, released the massive mammals, which breed quickly, with females producing 50-100 eggs each year. Due to the lack of predators on this continent, these slithery gluttons have become a threat to native animals, devouring more than 90% of the Everglades' small and medium-sized mammals. Some are more daring: during the course of three months, one killed and swallowed three deer-a doe and two fawns.

Feral Swine

Feral Swine
(Photo : Wikimedia Commons)

Feral swine are the same breed as field pigs, and they are descended from farm escapees and/or Eurasian or Russian wild boars introduced to the United States for sport hunting in the early 1900s. According to the US Department of Agriculture, there are at least 6 million wild swine distributed across 35 states.

They've been a nasty problem in the south, particularly in Texas, where their relentless rooting and voracious feeding damage crops, erode soil, and uproot tree seedlings, resulting in deforestation. Pseudorabies and swine brucellosis are two diseases they harbor. The US Department of Agriculture reports that invasive swine cause $1.5 billion in annual damage to all types of agriculture, including cotton, maize, and grains.

Also Read: Mammal Extinction Capital of the World: 5 of Australia's Critically Endangered Mammal Species

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