External Fertilization :
1. Fertilization or syn gamy occurs in the external medium(water),i.e., outside the body of the organism.
2. Example - Aquatic organisms like algae,bony fishes and amphibians.
3. The offspring are extremely vulnerable to predators threatening their survival up to adulthood.
Internal Fertilization :
1. Fertilization or syn gamy occurs inside the body.
2. Examples - Terrestrial organisms,belonging to fungi,animals like reptiles,birds,mammals and plants like bryophytes,pteridophytes,gymnosperms & angiosperms.
3. There is large number of sperms produced but the number of eggs is very low.