When oysters spawn, what is formed?

When oysters spawn, the correct answer is that free-swimming larvae are formed. This process begins with the release of gametes into the water, where fertilization occurs, resulting in fertilized eggs. These eggs then develop into larvae, which are called trochophore larvae initially, and eventually metamorphose into free-swimming larvae known as veligers.

It's important to note that spat refers specifically to juvenile oysters that have settled onto a substrate and begin their transformation into adult forms. This occurs after the larval phase, when the larvae have successfully found a suitable habitat to attach themselves and grow. Therefore, while spat is part of the lifecycle of oysters, the immediate outcome of spawning is the formation of free-swimming larvae, not spat.

Understanding the life cycle of oysters—from spawning to the development of larvae and eventually spat—highlights the reproductive process and the stages that oysters undergo for successful growth and development.