sentence2_structure: Invertebrates (and higher animals<>can be placed<>$$$two groups<>based<>on how they develop as embryos$$$they<>develop<>
sentence1: Because of the way the eggs develop, parthenogenetic embryos have only one type of sex chromosome, and of the two possibilities only ZZ embryos can survive.
sentence2: Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as embryos.
question: Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as what?