Embryonic stages of fish to mammals:
- Fish: Fertilization → Cleavage → Blastula → Gastrula with three germ layers → Development of notochord → Formation of organs → Hatching as fish fry.
- Amphibians: Similar to fish but undergo metamorphosis from aquatic tadpoles to terrestrial adults.
- Reptiles: Gastrulation → Organogenesis → Development of scales, limbs, and amniotic egg.
- Birds: Gastrulation → Specialization of features like beaks, wings, and feathers within the egg.
- Mammals: Similar to birds but viviparous → Placenta formation → Differentiation of tissues and specialized organ development → Live birth.
