ancestor
Noun

organism from whom one is descended.
cnidarian
Noun

large phylum of aquatic animals (such as jellies and corals) characterized by radial body symmetry and stinging tentacles.
evolution
Noun

change in heritable traits of a population over time.
genetic
Adjective

having to do with genes, inherited characteristics or heredity.
invertebrate
Noun

animal without a spine.
mammal
Noun

animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.
organism
Noun

living or once-living thing.
phylogenetics
Noun

study of how organisms relate to each other as they develop over time.
species
Noun

group of similar organisms that can reproduce with each other.
vertebrate
Noun

organism with a backbone or spine.

Articles & Profiles

  • Credits

    Media Credits

    The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

    Director

    Tyson Brown, National Geographic Society

    Author

    National Geographic Society

    Production Managers

    Gina Borgia, National Geographic Society
    Jeanna Sullivan, National Geographic Society

    Program Specialists

    Sarah Appleton, National Geographic Society
    Margot Willis, National Geographic Society

    Last Updated

    June 6, 2019

  • User Permissions

    For information on user permissions, please read our Terms of Service. If you have questions about licensing content on this page, please contact ngimagecollection@natgeo.com for more information and to obtain a license. If you have questions about how to cite anything on our website in your project or classroom presentation, please visit our FAQ page.

    Media

    If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media.

    Text

    Text on this page is printable and can be used according to our Terms of Service.

    Interactives

    Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.