(Here’s everything you need to know about alien species).

Invasive species are an absolute menace in today’s ecosystem and society. Here’s a look at some more of these species and how they have affected the invaded land.

• The black rat

The black rat is native to the Indian subcontinent, but spread across the globe in the 1st and 2nd centuries when Europeans traded extensively with India and adjoining regions. They hitchhiked on ships and created massive extinctions in every part they colonized. They have been especially harmful in

islands, owing to their weak defense against invaders. These rats have adapted very well to the current world as well, as they are found extensively in rural and urban areas.

• Killer algae

This is a weed that is native to Indian and western Pacific oceans. They were actively sought plants to beautify the aquariums in Europe and North America. Unfortunately, they escaped captivity. Since then, they have spread to pretty much every coastal region of the world (especially the Mediterranean) and has overtaken the producer niche of these ecosystems. Since local aquatic fauna is not adapted to eat these plants, they have suffered for want of food.

• Asian Tiger Mosquito (also called Aedes mosquito)

I know this bad boy quite well because it is widespread in my college campus (in fact, I just killed two in the last 5 minutes!). The Asian tiger mosquito is native to southeast Asia (so, I can’t blame anyone for inflicting them upon me), but has spread to 28 countries in the last two decades alone. They spread because of the tire trade (woah!); tires left to collect rainwater provide ideal breeding ground. They are especially dangerous because they are a vector for the Dengue virus, thus closely affecting human populations.

• Snakehead fish

Here’s one for the Hollywood movie makers! Similar to the likes of Piranhas from the movie Piranha 30D, the snakehead fish is a fish that swims, but can also breathe air and migrate onto land. They can survive on land for upto 4 days in search of other water bodies to colonize and lay up to 750,000 eggs per year. They have sharp dagger like teeth; they love blood. This, my friend, is the MOTHER of all invasive species! Originating in south Asian waters, they have easily spread throughout the globe, affecting food chains in the US as well.

• Zebra Mussel

This is a molluck native to the Caspain Sea, Black Sea and nearby lagoons. They live in fresh or brackish waters. In the 19th century, they migrated into European inland waters through man-made canals. Two centuries later, they have been spotted in the American continents as well. They massively affect our hydroelectric projects, and devour plankton, leaving little or no food to the native fishes of the area.