Beyond learning about the types of creatures that live in the ocean, preschoolers learn about the oceans themselves. Aquarium guides often explain to preschoolers that the world's oceans are the largest ecosystems on the planet, covering 70 percent of the Earth's surface. They also tell preschoolers that the oceans are made of saltwater, which is necessary for the marine creatures to survive.
Preschoolers also learn about other aquatic environments. Many aquariums have freshwater areas for freshwater organisms and other areas that mimic muddy swamps and estuaries (areas where fresh and saltwater mix) for animals that require those environments. Preschoolers learn that these aquatic areas, though they are much smaller than the saltwater environments of the Earth, still hold a variety of different lifeforms and are very important to humans.
Preschoolers who visit aquariums also receive information about the environmental and ecological challenges facing the world's aquatic biomes. They learn that the oceans and other bodies of water are threatened by human activities, such as pollution and excessive water usage. They also learn that many species of fish are endangered because of overfishing. Some aquariums teach preschoolers about water conservation and stopping pollution.
Preschoolers also see and learn about the many different species of aquatic animals that live in the world's marine and freshwater environments. They learn that not only fish, but reptiles, insects, amphibians, crustaceans and even some mammals live in water. They learn that these creatures live in different parts of the world at varying depths of water and that the animals spend all or most of their lives underwater.