What is Alien Invasive Animal Species? Why Do Alien Species Become Invasive? (Download PDF)


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Zoological Survey of India (ZSI) for the first time compiled a list of 157 alien invasive animal species excluding invasive microbe species. Alien species can arrive by human activity, either deliberate or accidental. Non-native species can have various effects on the local ecosystem.

Alien Invasive Animal Species india

Alien Invasive Animal Species India

Alien Invasive Animal Species india

What is Alien Invasive Species?

  • Alien species (IAS) have been introduced or spread outside their natural past or present distribution. They are also called introduced species.

  • Invasive alien species are plants, animals, pathogens causing economic or environmental harm or adversely affect human health. In particular, they adversely affect biodiversity, including decline or elimination of native species - through competition, predation, or transmission of pathogens - and the disruption of local ecosystems and ecosystem functions.

  • Since the 17th century, invasive alien species have contributed to nearly 40 % of all animal extinctions for which the cause is known (CBD, 2006).

Why Do Alien Species Become Invasive?

Invasive plants have a few things in common:

  • They lack enemies, in that not many animals will eat them and few diseases affect them in their new environment

  • They produce seeds or berries prolifically, which are often bird-dispersed

  • They are “generalists, ” meaning that they can grow in many different conditions

  • They grow quickly

Characteristics of Invasive Species

  • Rapid reproduction and growth

  • High dispersal ability

  • Ability to survive on various food types and in a wide range of environmental condition

  • Ability to adapt physiologically to new conditions (phenotypic plasticity).

  • Ability of invasive plants comes from inherent genetic variation rather than new mutations.

  • Adaptability of invasive plants lies in their quick genetic changes in a new environment, rather than the species’ inherent ability to tolerate many conditions.

Key Facts on ZSI List of 157 Alien Invasive Animal Species

Of total 157 species:

  • 58 are found on land and in freshwater habitats- 19 species of fish, 31 species of arthropods, 3 of molluscs and birds, 1 of reptile and 2 of mammals

  • 99 are found in marine ecosystem: Genus Ascidia accounts for maximum number of species (31) Followed by:

    • Arthropods (26)

    • Annelids (16)

    • Cnidarian (11) Bryzoans (6)

    • Molluscs (5)

    • Ctenophora (3)

    • Entoprocta (1).

Important Alien Species

  • Achatina fulica (African apple snail) :

    • Most invasive among all alien fauna in India.

    • This mollusc was first reported in Andaman and Nicobar Islands.

    • Now found all across country threatening habitats of several native species.

  • Paracoccus marginatus (Papaya Mealy Bug) :

    • Native to Mexico and Central America.

    • Believed to have destroyed huge crops of papaya in Assam, West Bengal, and Tamil Nadu.

  • Phenacoccus solenopsis (Cotton Mealybug) :

    • Native of North America.

    • Severely affected cotton crops in the Deccan.

  • Pterygoplichthys pardalis (Amazon sailfin catfish) : It is responsible for destroying fish populations in the wetlands of Kolkata.

- Published/Last Modified on: January 3, 2018


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