Giant salamanders are aquatic species that hunt in fast-moving Asian rivers and streams. They don't have gills to help them gather oxygen underwater; instead they've adapted to their environment in a way that lets them breath in and out of the water. This adaptation seems to work well for them -- they can live to about 100 years old in the wild.
There are two main types of giant salamanders, and they are similar in essentially every aspect except size. Japanese salamanders grow up to about 55 pounds, while Chinese giant salamanders can grow up to 66 pounds. Both are almost exclusively aquatic; both have poor eyesight, relying on their sense of smell and touch to hunt. Smell is about all their noses are good for, as they're not used much for breathing.
Giant salamanders have small nostrils on the end of their noses, and the nostrils connect to lungs that process oxygen. They use their nostrils and lungs when they leave the water to hunt prey along the sides of the rivers. However, the majority of their lives they spend in water, leaving their noses out of the breathing equation.
Under water, a giant salamander absorbs oxygen through its skin. It has specially designed folds of skin along each side to increase the skin's surface area, allowing the salamander to draw in more oxygen. This method of breathing bypasses the lungs, allowing oxygen directly into the salamander's system.
Types of Water
Not all water is created equal when it comes to oxygen levels. Giant salamanders tend to prefer colder water, which has a higher concentration of oxygen than warm water. They like fast-moving streams, where the movement of the water keeps them well oxygenated. Pollution is a problem for giant salamanders, as it reduces the water's oxygen supply. Pollution, hunting and human encroachment into the habitat of giant salamanders have gained these salamanders critically endangered status.