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How does external fertilization occur in fish and amphibians?

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Study the different ways mushrooms release spores and watch mold hyphae spread across bread — Reproduction Fungi produce billions of spores that give rise to new generations of fungi.

In biology, external fertilization is a reproductive strategy where the union of male and female gametes occurs outside the bodies of the parents. This process is common among many aquatic species, particularly fish and amphibians, which typically breed in water.123

External Fertilization in Fish

Most bony fishes are oviparous, meaning they lay eggs. During reproduction, females release a large number of eggs into the water—either into the open water column or onto a substrate like rocks or plants. Simultaneously, males release milt, a milky substance containing sperm, directly into the water. The sperm then fertilizes the eggs externally. Because this process relies on random collisions in the water, the gelatinous coats surrounding the eggs often help trap sperm to increase the likelihood of successful fertilization.42

External Fertilization in Amphibians

Many amphibians, such as most frogs and toads, also utilize external fertilization. In these species, the male and female typically shed their sex cells into the water, where fertilization occurs. Unlike many fish, some amphibians engage in amplexus, a mating embrace where the male positions himself to fertilize the eggs as the female extrudes them. While some amphibians have evolved internal fertilization methods, the majority of anurans rely on this external process to produce their gelatinous eggs.5163