Internal fertilization involves the union of sperm and egg within the female’s body, while external fertilization occurs outside the female’s body, typically in water. Internal fertilization is common in many terrestrial animals, including mammals, birds, and some reptiles, while external fertilization is more prevalent in aquatic organisms like fish and amphibians.
Here’s a more detailed comparison:
Internal Fertilization:
Location:
The union of gametes (sperm and egg) takes place inside the female’s reproductive tract.
Mechanism:
Sperms are deposited within the female’s body, often through copulation, and then swim to meet the egg.
Examples:
Mammals (humans, dogs, cats), birds (chickens, ducks), reptiles (snakes, lizards).
Advantages:
Increased protection for the developing embryo, lower risk of predation and dehydration, and higher chances of successful fertilization.
Disadvantages:
Requires more complex reproductive systems and mating behaviors, and the female has less control over the timing and location of fertilization.
External Fertilization:
Location:
The union of gametes takes place outside the female’s body, usually in a watery environment.
Mechanism:
Both eggs and sperms are released into the environment, where they come together and fuse.
Examples:
Fish (salmon, goldfish), amphibians (frogs, toads), and some invertebrates (sea stars, jellyfish).
Advantages:
Large numbers of offspring can be produced, requiring less energy for mating, and reduced competition between parents and offspring.
Disadvantages:
High mortality rates of eggs and sperm due to environmental factors, predation, and difficulty in locating mates.