Fertilization is the union of a sperm and an egg, beginning the development of a new organism. This lesson compares external and internal fertilization and explores how different reproductive strategies affect offspring survival.
In external fertilization, sperm and eggs meet outside the female’s body. It usually occurs in water, which prevents eggs from drying out. Many aquatic animals reproduce this way, including fish, crustaceans, mollusks, squid, echinoderms, and frogs.
All flashcards
What is external fertilization?
The union of sperm and egg outside the female’s body; it commonly occurs in water, where eggs are less likely to dry out.
What happens during spawning?
One or more females release eggs and one or more males release sperm in the same area at about the same time.
How does ovoviviparity nourish an embryo?
The fertilized egg remains inside the parent, but the embryo receives nourishment from the egg yolk rather than directly from the parent.
What is viviparity?
The embryo develops inside the female, receives nourishment from the parent, and the young are born alive.
What is a spermatheca?
A specialized sac in some insects that stores sperm after mating.
Quiz questions
Why is water a suitable environment for many species that use external fertilization?Answer: It helps prevent released eggs from drying out.
Which environmental cues may trigger spawning in some animals?Answer: Changes in water temperature or daylight duration.
What is one possible benefit of broadcast spawning?Answer: It can mix genes from many individuals and help offspring disperse.
How can sperm storage in a spermatheca benefit some insects?Answer: It can allow fertilization when conditions are favorable for offspring.
What is a cloaca in many non-mammalian vertebrates?Answer: A shared opening for the digestive, excretory, and reproductive systems.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.