Guess the Embryo

  • By Rachel VanCott
  • Posted 10.26.09
  • NOVA

Any animal, be it a blue whale, botfly, or human, starts out as a single, fertilized cell. Then the cell divides, differentiates, and ultimately develops into a full-fledged animal according to a special set of genetic instructions–a "toolkit" that tells the embryo how and where to develop limbs and organs. All animals on Earth use essentially the same toolkit, so embryos of different species can appear startlingly similar to one another. Here, try to match a series of embryos to their adult forms, and then watch each creature develop during a portion of its early growth.

Launch Interactive

See if you can tell what four similar-looking embryos will become, and watch each develop.



(human embryo)
Omikron/Photo Researchers, Inc.
(embryo 1, embryo 1 developmental stages, embryo 2, embryo 2 developmental stages, embryo 3, embryo 3 developmental stages)
Courtesy Seth Ruffins, Russell Jacobs, Benoit Boulat, Melanie Martin, and the California Institute of Technology
(goldfish, terrier, ferret, lamb, quail, kangaroo, parrot, iguana, hedgehog, pig, snail)
© Eric Isselée/istockphoto
© Andy Gehrig/istockphoto
© Cindy Singleton/istockphoto
© Brent Melton/istockphoto
(embryo 4, embryo 4 developmental stages)
Courtesy Chris Cretekos and Richard R. Behringer
© Ryan Pike/istockphoto
(bat) ©
Joe McDonald/Corbis

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