Who undergoes external fertilization?

Outside fertilization usually takes place in aquatic environments where both eggs and sperm are released into the water. After the sperm reaches the egg, fertilization takes place. Most external fertilization occurs during the spawning process, when one or more females release their eggs and male sperm in the same area at the same time. The release of reproductive material can be triggered by water temperature or the duration of daylight. Nearly all fish, crustaceans (such as crabs and shrimps), molluscs (such as oysters), squid and echinoderms (such as sea urchins and sea cucumbers) come from external fertilization.