Embryonic Development Your Inner Fish Embryo Chapter Embryonic Development Investigation 2.4

Early development

Intermediate development

Late development

adult

All Stages

Big ideas The five vertebrate embryos we observed all start out very similar, because all vertebrates share a common ancestor. As the embryos grow the dna for the specific species start to “turn on” instructions or “turn off” instructions. For example our human dna says, “build a big brain” and “Do not build a tail”, whereas an alligator’s dna says, “build a long powerful tail” and “do not build a big brain”. This is similar to how stem cells start similar and general and then specialize into different body cells. Embryos start out general and then specialize into the bodies of different species. If there are organs or structures the species doesn’t need, they often do not develop beyond the early stage of the embryo.