Here are some examples:
* Fish: Most fish species release their eggs and sperm into the water, where fertilization occurs.
* Amphibians: Frogs and toads lay their eggs in water, and the male releases sperm to fertilize them.
* Invertebrates: Many marine invertebrates, like sea urchins and starfish, release their eggs and sperm into the water for fertilization.
External fertilization is a common strategy for animals in water because:
* Large numbers of eggs: It allows for the production of large numbers of eggs, increasing the chances of survival for some of the offspring.
* No need for direct contact: It eliminates the need for males and females to directly interact for fertilization.
However, external fertilization also comes with some drawbacks:
* Environmental dependence: The success of fertilization depends on the environment, including water quality, temperature, and the presence of predators.
* Lower survival rate: Fewer offspring survive compared to internal fertilization, where the eggs are protected inside the female's body.