Invasive species are living organisms that are introduced to a place where they are not native. They become part of ecosystems outside their original range. These species are found in many regions.

Zebra mussels, originally from parts of Europe and Asia, spread into North American lakes through ships. Some plants and animals are moved by travel, trade, or transport. In new environments, invasive species may spread quickly and become common.

Invasive species are studied in environmental science. They are tracked in ecosystems around the world.