Why do many amphibians lay their eggs in standing water?

Many amphibians lay their eggs in standing water because they lack the specialized protective structures—specifically a shell and the embryonic membranes known as the amnion and allantois—that are necessary to maintain physiological balance on land. Without these features, their eggs are susceptible to desiccation and must be kept in moist environments to survive and develop.1

For many species, standing water provides the essential medium for the larval stage of their biphasic life cycle. In this environment, the eggs hatch into free-living tadpoles or larvae that must find their own food and escape predators while they complete their development. Depositing eggs in water also allows for efficient gas exchange and, in some cases, provides access to highly oxygenated areas, such as the water surface, which supports the development of the embryo. While some amphibians have evolved parental care strategies to bypass the need for permanent water bodies, the majority rely on aquatic habitats to ensure the survival of their offspring.2341