👉 Siphonostomous is a type of animal that has two sets of gills located in opposite sides of its body. This means that it can produce and extract water from both lungs at once, allowing it to breathe more efficiently than if it had one set of gills for each lung. This adaptation helps the siphonostomous animal to survive in environments where it has to operate with limited oxygen, such as those found in deep-sea trenches or underwater caves.