25 Most Invasive Creatures On Earth

Commonly called the comb jelly or sea walnut, it is indigenous to temperate, subtropical estuaries along the Atlantic coast of North and South America. In the early 1980s, it was accidentally introduced via the ballast water of ships to the Black Sea, where it had a catastrophic effect on the entire ecosystem. In the last two decades of the twentieth century, it invaded the Azov, Marmara, and Aegean Seas and was recently introduced to the Caspian Sea via the ballast water of oil tankers.

The Nile perch is a large freshwater fish that can grow up to 200 kg and reach up to two meters in length. It was introduced to Lake Victoria in 1954, where it has contributed to the extinction of more than two hundred endemic fish species through predation and competition for food.

Believe it or not, the domesticated cat, which can be traced back three thousand years to the eastern Mediterranean, is one of the most invasive creatures on Earth. Considering the extent to which cats are valued as pets, it is not surprising that they have since been translocated by humans to almost all parts of the world. Notable predators, cats threaten native birdlife and other fauna, especially on islands where native species have evolved in relative isolation from predators.

The cannibal snail was introduced to Indian and Pacific Ocean islands from the 1950’s onward as a biological control agent for the giant African snail. As its name suggests, this snail will eat anything in its path, even its own kind.

Eriocheir sinensis (its scientific name) is a migrating crab that has invaded Europe and North America from Asia. During mass migrations it contributes to the temporary disappearance of native invertebrates. It modifies habitats by causing erosion due to its intensive burrowing activity and costs fisheries and aquaculture several hundred thousand dollars a year by consuming bait and trapped fish as well as by damaging gear.

The Caribbean tree frog is a relatively small tree frog native to Puerto Rico. Their loud call is the main reason they are considered a pest, since their two-note “co-qui” can attain nearly one hundred decibels at 0.5 meters. Caribbean tree frogs are also known for having a voracious appetite and there are fears in Hawaii that endemic insect and spider species are at risk due to this frog’s unusual appetite.

The walking catfish is native to Southeast Asia and has been introduced in many places for fish farming. The walking catfish (named for its ability to move over land) is an opportunistic feeder and can go for months without food. During a drought large numbers of walking catfish may congregate in isolated pools and consume other species, even causing their extinction.

Originally found in far north Pacific waters and areas surrounding Japan, Russia, North China, and Korea, the northern Pacific sea star has successfully invaded the southern coasts of Australia and has the potential to move as far north as Sydney. The sea star will eat a wide range of prey and has the potential for ecological and economic harm wherever it finds itself.

Raspberry crazy ants have invaded native ecosystems and caused environmental damage from Hawaii to the Seychelles and Zanzibar. On Christmas Island in the Indian Ocean, they have formed multi-queen super colonies. They are also decimating the red land crab (Gecarcoidea natalis) populations. Crazy ants also prey on, or interfere in, the reproduction of a variety of arthropods, reptiles, birds, and mammals on the forest floor and canopy.

Anopheles quadrimaculatus (as it is known scientifically) is a mosquito that is responsible for most cases of malaria in North America. They are typically found at sites with abundant rooted aquatic vegetation, such as rice fields and adjacent irrigation ditches, freshwater marshes, and the vegetated margins of lakes, ponds, and reservoirs.

The Asian long-horned beetle is a large wood-boring beetle that is native to countries in Asia, including Japan, Korea, and China. It was first introduced to the US back in the mid-’90s and twenty years later it threatens 30–35 percent of the trees in urban areas of the eastern US. The economic, ecological, and aesthetic impacts on the United States would be devastating if the beetle continues to spread.

The Asian tiger mosquito is spread via the international tire trade due to the rainwater retained in the tires when stored outside. In order to control its spread such trading routes must be highlighted for the introduction of sterilization or quarantine measures. The tiger mosquito is associated with the transmission of many human diseases, including dengue fever, the West Nile virus, and Japanese encephalitis.

Burmese pythons might be a popular pets because of their attractive color pattern, reputed docility, and the allure (for some, anyway) of owning a giant snake. As predators, however, Burmese pythons pose a threat to endangered wildlife in South Florida. Their rapid and widespread invasion is facilitated by aspects of their natural history including their diverse habitat use, broad dietary preferences, long life span, high reproductive output, and ability to move long distances.

Don’t be fooled by this bird’s striking colors. The European starling is a notorious competitor and will aggressively lay claim to native bird nesting sites, kicking out the resident birds and their eggs. They compete with native birds for space and food, but also carry disease, ticks, and mites that are spread to native bird species and humans. Starlings are also a threat to farmers since flocks of birds can wipe out crops.

Even though movies such as the 1974 film Killer Bees have succeeded in instilling fear, the bees’ venom is no more toxic than that of the European honeybee. They are, however, known to be highly aggressive and sting a lot more, with some victims receiving more than a thousand stings. In addition to being a threat to humans, they are also relatively lazy when it comes to producing honey, making them a threat to agricultural stability as well.

The gray squirrel may be cute and fuzzy to look at, especially in Stanley Park in Vancouver, but it is an invasive mammal in British Columbia that is ranked by the Invasive Species Specialist Group (ISSG) as one of the Top 100 Invasive Species in the world. This small mammal has big ecological impact, often causing disease (parapoxvirus), and is responsible for displacing native birds from their nesting habitat, and eating the birds’ eggs and nestlings.

Zebra mussels are small, fingernail-sized creatures that attach to solid surfaces in water. A single female can produce 100,000 to 500,000 eggs per year, contributing to their successful invasions. These develop into microscopic, free-living larvae that begin to form shells, taking over huge lakes.

The northern snakehead, as it is also known, is a type of snakehead fish native to China, Russia, North Korea, and South Korea. In Europe, the first report of the species was from Czechoslovakia (the Czech Republic) in 1956. In the United States, the fish is considered to be a highly invasive species, which has led to major media coverage and two horror films.

The cotton whitefly has been reported on all continents except Antarctica. It is believed the cotton whitefly has spread throughout the world through the transport of plant products that were infested with them. Once established, it quickly spreads and through its feeding habits and the transmission of diseases, it causes destruction to crops everywhere.

The feral European rabbit is one of the most widely distributed and abundant mammals in Australia. It causes severe damage to the natural environment and to agriculture. European rabbit control is complicated because of welfare and harvesting issues, and because both native and introduced predators feed on feral rabbits in many parts of Australia. An invader and victim at the same time? Pretty much.

Cane toads were introduced to many countries as biological control agents for various insect pests on sugarcane and other crops. The cane toads have proved to be pests themselves. They will feed on almost any terrestrial animal and compete with native amphibians for food and breeding habitats. Their toxic secretions are known to cause illness and death in domestic animals that come in contact with them, such as dogs and cats, and wildlife such as snakes and lizards.

A native of the Indian subcontinent, the so-called black rat has now spread throughout the world. It is widespread in forests and woodlands as well as being able to live in and around buildings. It will feed on and damage almost any edible thing. To get an idea of how invasive this creature is, keep in mind it’s most frequently identified with catastrophic declines of birds on islands.

When the brown tree snake was accidentally introduced to Guam it caused the local extinction of most of the island’s native bird and lizard species. It also caused “cascading” ecological effects by removing native pollinators, causing the subsequent decline of native plant species. The fragility of the ecosystems of other Pacific islands to which cargo flows from Guam has made the potential spread of the brown tree snake from Guam a major concern.

Beautiful and deadly the Lionfish are known for their voracious appetite. Their over abundance is threatening life on coral reefs which serve as habitats for other fish species. Native to the Pacific Ocean, the Lionfish was traded for their bizarre appearance which has led to their spread throughout the Gulf of Mexico, the Atlantic, and the Caribbean.

With a continuously growing population of over seven billion, human beings have been responsible for the extinction of various living organisms—from animals and insects to plants and sea life. Additionally, no other living creature has damaged the atmosphere, nature, and other humans the way we have.