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If you want to find out whether mammals have gills or lungs then you’ve come to the right article. As, in this article, you’ll find the answer to this question and after you’ve read the answer to the main question then I’ll share the answers to a few more closely related questions as well to extend your knowledge further. I hope you learn a lot from this article! Do Mammals Have Gills Or Lungs? All mammals have lungs as their primary breathing organs, and they do not have gills like, for example, fish have. Even mammals that spend their lives underwater like whales and dolphins breathe through their lungs by periodically surfacing and taking in air from above the water line. Why Do Mammals Have Lungs and Not Gills? Terrestrial bipedal humans are, for example, incapable of breathing through gills if we would have them because, on land, the oxygen-absorbing projections on a pair of gills do not float. Instead, they collapse together, reducing the surface area for oxygen absorption and causing suffocation. This is also the reason why fish cannot survive for long periods out of the water. We cannot breathe underwater although water consists of oxygen because the oxygen in H2O is so tightly bound to its hydrogen atoms that it remains inaccessible to us. Mammalian lungs lack the surface area to extract oxygen from the water. But even if humans had much bigger lungs, it would still take huge amounts of energy to filter out the oxygen and we can better use this energy to maintain our warm body temperature. Do All Marine Mammals Have Lungs and Not Gills? All marine mammals have lungs and must surface regularly to breathe oxygen. This includes whales, dolphins, porpoises, seals, sea lions, walruses, manatees, polar bears, and sea otters. Only one type of fish is known to have both lungs and gills which is the African Lungfish. These remarkable creatures spend most of their life underwater but can survive for three to five years on land without any food. Do Mammals Have Embryonic Gills? Though there are some conflicting views, most agree that mammals never show compelling evidence of embryonic gills in the womb. Certain structures around the jaw and ears are believed to have a slight vestigial resemblance to pharyngeal (gill-like) folds but, if they ever functioned like true gills, they have evolved to be something very different today. So, mammals don’t have embryonic gills. Which Mammals Have Gills? There are no mammals with gills living on planet earth. Though a select few marine animals such as the lungfish and the salamander have both lungs and gills. Land crabs are sometimes mistaken for a marine species with lungs because they can technically ‘breathe’ out of water. But they aren’t using lungs like ours. They have specially designed gills that inflate and become temporary ‘lungs’ for a finite time when they’re out of the water. Why Can Whales Not Breathe Underwater? Whales cannot breathe underwater for the same reasons humans and all other mammals cannot breathe underwater. Our bodies are not designed for it. We have lungs for breathing on land instead of aquatic gills. Like human lungs, whales’ lungs cannot extract enough oxygen from the water in each new breath. Being warm-blooded, they require tremendous amounts of oxygen to maintain their core temperature and survive life at sea. The only way they can take in enough oxygen is by repeatedly surfacing and breathing outside of the water. Check the video below if you want to find out what's inside of a whale's blowhole. Why Have Whales and Dolphins Not Evolved to Have Gills? Whales and dolphins never needed to develop gills. Evolution always takes the fastest route and, according to marine biologists, the evolution of gills would have taken significantly more time than evolving the physiological ‘quirks’ required for whales and dolphins to survive underwater. Adaptation of the existing lung structures was simply a faster way for marine mammals like dolphins and whales to evolve. Evolving to use gills would require millions more years of incremental adaptations and a long transition to a cold-blooded body. How Do Mammals Breathe? Mammalian breathing occurs in the respiratory system which includes the two lungs and several muscles and airways designed to move oxygen in and carbon dioxide out. The airways are lined with microscopic hairs that filter the oxygen and remove microbes before it enters the lungs. The mammalian system relies on a large muscle at the base of the lungs called the diaphragm. It pulls the lungs downwards to increase their volume and draw oxygen inside. When the diaphragm presses upward, the lungs contract, and carbon dioxide get exhaled as waste. Muscles in the rib cage work in coordination with the diaphragm to continually expand and contract the lungs in a perfect rhythm that keeps us breathing without us even having to think about it. How Do Mammals Breathe Underwater? Marine mammals such as dolphins and whales breathe in precisely the same way as chimpanzees, humans, dogs, horses, or gerbils. We all breathe through our lungs, the only difference is how often we do this. Marine mammals must surface regularly and lift their blowhole or spiracle out of the water to inhale. On average, they do this every 5 to 8 minutes though it varies depending on the size of the animal and the type of activity it is engaged in. Dolphins are known to surface every 4 to 6 minutes but have been observed taking much longer breaths while hunting. Whales are the largest marine mammal and can wait around an hour between breaths if necessary. But they tend not to wait so long unless there’s a specific motivation like being engaged in a challenging hunt or hiding from orca predators. Check out the video below if you want to find out how marine mammals can hold their breath for so long. How Do Whales and Dolphins Breathe? The biggest difference between the way whales and dolphins breathe and the way humans breathe is what’s known as conscious breathing. Humans and most other mammals breathe involuntarily. We can control some aspects of our breathing but we don’t need to be awake to take in oxygen. We have to put more effort into not breathing. This is entirely different from whales and dolphins as both species are conscious breathers. They breathe using mammalian lungs as we do but in the opposite fashion. Every breath is a controlled and conscious decision that requires the animal to stay at least partially alert throughout every moment of its life. For this reason, dolphins, whales, and some other sea mammals are incapable of true unconsciousness. Do All Mammals Breathe? All mammals living on planet earth breathe oxygen through specially adapted lungs. Even massive marine mammals like dolphins and whales breathe air by surfacing and taking in oxygen from above the water line. What Mammals Breathe Through Their Mouths? Almost all mammals are capable of breathing solely through their mouths despite nasal breathing being the preferred and most efficient method of respiration. Nasal breathing has various benefits such as warming cold air before it reaches the lungs and filtering out more airborne bacteria. However, it isn’t always as easy as it should be. Humans, dogs, rabbits, cats, cows, tigers, elephants, and a host of other mammals can switch to mouth breathing when required. It’s a valuable skill for times when the upper airway is obstructed, the body is overheating and needs to be cooled rapidly or large amounts of oxygen are required to fuel an intense burst of movement. What Animals Have Gills? Almost all aquatic creatures (besides the large sea mammals) breathe using gills. Sharks, octopuses, prawns, various other fish species, giant clams, and practically all marine-based mollusks and insects have gills or gill-like organs. What Animals Have Lungs? All mammals breathe through a pair of specially adapted lungs. Although there is huge variation in size, shape, and capacity, all the lungs that are present in animals all share the same basic structure and function in the same way. From the biggest elephant to the smallest snake or spider, we are all terrestrial land-dwelling animals that depend on lungs for survival. The only animals that don’t have lungs are marine creatures like sharks, octopuses, prawns, giant clams, and the many other species of fish that exist in bodies of water. If it lives in the water and it’s not a mammal, you can bet it breathes through gills.