Salmon (External Fertilization)
* Location: Fertilization occurs externally, in the water.
* Process:
* Female salmon release eggs into the water (spawning).
* Male salmon release sperm into the water, which then fertilizes the eggs.
* The fertilized eggs develop into larvae and eventually hatch.
Sheep (Internal Fertilization)
* Location: Fertilization occurs internally, within the female reproductive tract, specifically in the oviduct.
* Process:
* The female sheep releases an egg from her ovary (ovulation).
* The male sheep deposits sperm into the female's reproductive tract (mating).
* Sperm travel through the uterus and into the oviduct where fertilization takes place.
* The fertilized egg (zygote) then travels down the oviduct and implants in the uterine wall, where it continues to develop into a fetus.
Key Differences
* Location: Salmon fertilize externally, while sheep fertilize internally.
* Sperm Delivery: Salmon release sperm directly into the water, while sheep rely on internal fertilization.
* Offspring Development: Salmon eggs are laid and develop in the water, while sheep offspring develop inside the mother's body.
Evolutionary Context
These differences reflect the evolutionary adaptations of each species to their respective environments.
* Salmon: External fertilization in water is a common strategy for aquatic animals, allowing for large numbers of offspring to be produced.
* Sheep: Internal fertilization allows for greater protection and control of the developing embryo, as well as a more efficient use of resources.