Turtles are excellent divers, but from time to time they must go back to the surface to breathe. As turtles have a carapace, they can not extend and contract the ribs to breathe. Instead, they use their fin muscles and swimming movement to bomb air from inside to outside of the lungs. Many turtles species can not dive in deeps because their carapace is so hard that it might crush as they are diving because of water pressure. But some other species are adapted to deep-diving. These marine turtles keep huge amounts of oxygen in their muscles and blood instead of keeping them in the lungs. They can dive for a very long time in the deep, most of the time foraging, escaping from predators or to regulate their body temperature. These species can handle the pressure because their carapace is not that hard, so it allows the body to compress and not to be crushed by water pressure.
Most aquatic snakes are known to dive near the surface, where water is warmer and helps them to regulate their body temperature. But some other species are adapted to dive up to 250 meters deep where they can forage over a wider amount of prey. Independently of how deep they can swim, all of these aquatic animals must go back to the surface for gas exchanging. They can hold the breath for 5 or 6 hours, but after that period they must breathe. Some marine snakes are adapted to deep diving: their bodies are very laterally comprised and they can face the breathing problem through skin gas exchanging. Although they have developed these adaptations, at some point they must breathe.
Water Lilies need light and warm water to grow. They grow fast and colonize illuminated places, in warm and shallow water. The deeper the plant is located, the slower it will grow. These plants can not live in waters over five feet deep, because deep water is cold and poorly lighted, and tubers and rhizomes take a long time to establish in these places.
Mangrove trees have roots called pneumatophores that allow them to take oxygen from the air and produce gas exchange. They can resist a periodic submersion but they need to drain. If these roots are constantly underwater they can not accomplish their respiratory function and the tree eventually dies. These species have different strategies to deal with salt, one of excreting it by their leaves. If leaves are underwater, they are not able to do this, increasing salt levels in their system.
