Activity for Keith Morrison‭

Type	On...	Excerpt	Status	Date
Answer	—	A: Would there be any major disadvantages for a species to have six legs instead of four? There's at least one paper suggesting the reason for four limbs is because of the way embryos develop. Basically, an embryo's cells develop early on into three layers: ectoderm, mesoderm, and endoderm. The endoderm becomes the digestive tract, the ectoderm the skin and nervous tissue, and the mesode... (more)	—	about 6 years ago