The baiji, or Chinese river dolphin, was native only to China's Yangtze River. The baiji was declared "functionally extinct" in 2006.

Illustration by Else Bostelmann, National Geographic

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  • On December 12, 2006, biologists declared the baiji (Chinese river dolphin) "functionally extinct." The international authority on endangered species (the IUCN) classifies the baiji as “critically endangered,” although there have been no confirmed baiji sightings in recent years.

    Baiji were freshwater dolphins, one of only four known species. They were indigenous to China's Yangtze River. Their numbers fell from more than 6,000 in the 1950s to about 400 by 1984. Factors contributing to their extinction include fishing, dams, and industrial pollution.

  • Term Part of Speech Definition Encyclopedic Entry
    biologist Noun

    scientist who studies living organisms.

    dam Noun

    structure built across a river or other waterway to control the flow of water.

    endangered species Noun

    organism threatened with extinction.

    Encyclopedic Entry: endangered species
    extinct Adjective

    no longer existing.

    factor Noun

    element contributing to an event or outcome.

    fish Verb

    to catch or harvest fish.

    freshwater Adjective

    having to do with a habitat or ecosystem of a lake, river, or spring.

    indigenous Adjective

    characteristic to or of a specific place.

    Encyclopedic Entry: indigenous
    industrial Adjective

    having to do with factories or mechanical production.

    International Union for the Conservation of Nature (IUCN) Noun

    environmental organization concerned with preserving natural ecosystems and habitats.

    pollution Noun

    introduction of harmful materials into the environment.

    Encyclopedic Entry: pollution