The embryos of reptiles (including birds) and mammals have systems of extraembryonic membranes. What are the functions of these membranes, and how do fish and frog embryos survive without them?

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1. Identify the types of extraembryonic membranes present in reptiles and mammals, such as the amnion, chorion, yolk sac, and allantois, and understand their individual functions. The amnion protects the embryo in a fluid-filled cavity, the chorion facilitates gas exchange, the yolk sac provides food from the yolk, and the allantois handles waste and also aids in gas exchange.
2. Examine the environmental differences between terrestrial and aquatic habitats where these embryos develop. Reptiles and mammals typically lay eggs or carry their young in environments where desiccation (drying out) can be a risk, thus necessitating these protective and supportive membranes.
3. Understand the reproductive strategies of fish and frogs, which generally lay a large number of eggs in aquatic environments. The water provides a medium that supports the eggs and embryos, reducing the need for protective membranes against desiccation.
4. Explore how the gelatinous coatings of frog eggs and the multiple layers of membranes around fish eggs serve as protective barriers against physical damage and predation, and also how these layers facilitate the exchange of gases and disposal of waste.
5. Compare and contrast the developmental stages of these different groups of animals, noting how the presence or absence of extraembryonic membranes correlates with other adaptations to their respective environments, such as egg quantity, parental care, and embryonic development speed.