Similar structures are present in the embryos of fish, salamanders, turtles, chickens and pigs. in fish, these structures develop into gills but in the other organisms they either disappear or develop into other body parts later in embryonic development. which of these statements below best explains the presence of these structures in the embryos of all five species? a) the embryos of the five species are similar in size. b) breathing structures are similar among the young of the five species. c) the five species have a common ancestor with these embryonic structures. d) the reproductive mechanisms are similar among the adults of the three species.