Are Penguins Mammals?
Birds or mammals? What penguins are actually? This is a very perplexing and confusing question for many researchers and analysts. Penguins are considered fish because they can survive in water and spend most of their life in water. Research shows that they spend more than half of their lives in water. On the other hand, they have knees and live on land as well just like mammals. They can live in water and land both, so they can be amphibians… Like birds they have feathers. Now how to decide what penguins actually are??
Let’s discuss this problem in detail and find the correct answer.
- What are mammals?
There are certain characteristics on the basis of which we define mammals. Mammals are vertebrates and belong to the class Mammalia. They have three bones in the middle ear, a neocortex in the brain and true hairs. The female members of this class feed their young ones with milk which is produced by mammary glands. Placentals are the mammals that have the placenta for the provision of food and nutrition to the fetus during the gestation period. They give birth to babies rather than eggs. Most mammals have quadrupled body posture but some mammals exhibit bipedal locomotion.
- What are birds?
These are the warm-blooded, egg-laying vertebrates. They have wings, feathers, and two legs. They have toothless beaks and they make sounds using syrinx which is the specialized structure for the production of sounds in them.
- If penguins are mammals, they should give birth to young ones.
Yes, let me clear one thing that mammals always give birth to young ones rather than laying eggs. Penguins lay eggs. The female emperor or king penguin lays one egg at a time while all other species of penguins lay two eggs at a time. All penguins store eggs in their legs for warmth and protection. But emperor penguin is the exception, he uses his feet for this purpose. It is the duty of the male to incubate the egg for about two months. The female usually lays eggs in May and June.
- If penguins are mammals, they should nurse their young ones with milk.
It is the feature of mammals that they feed their young ones with milk. But penguins do not feed their young ones. Instead, they feed their young ones with krill( they are tiny crustaceans), squid and fish. They are basically carnivores and depend on meat only. This is another evidence that we cannot blindly consider them mammals. Although they have knees, this is not the trait that can add them in class Mammalia.
- They are warm-blooded like mammals.
Mammals are warm-blooded and they have to keep their temperature in a certain range under all circumstances and it is necessary for their survival. Can this be the reason for considering them mammals? No. I can give you a satisfactory answer. Birds are also warm-blooded, then they can also be included in birds… So why only mammals? This is, again, a very weak point of adding penguins in class Mammalia.
- If penguins are mammals, they should have mammary glands.
Obviously, if penguins are mammals, then they should have mammary glands to feed their young ones and for the production of milk. So as we have discussed earlier, they lack this feature.
- Huddling behavior of penguins.
Penguins usually become close and close together forming groups with their young ones in the middle section. The purpose is to provide maximum protection to their babies. This phenomenon is called huddling. This protective behavior resembles mammals because mammals are also very protective in their nature. Such slight similarities are unable to add the penguins in class Mammalia but this doesn’t alter the overall definition of mammals and cannot add penguins in class Mammalia.
- Penguins have an upright stance like mammals.
This thing may confuse us. Penguins have a very straight posture and it seems as if they exhibit bipedal locomotion like mammals. They have an upright stance and move very similar to human beings and this again leads to misconceptions. But we should think that this feature is only physical and not the distinguishing one. They move at the right angle with the surface. They can run and walk slowly. They seem very shy, humble and gentle. Their bodies are adapted for swimming so they look awkward while walking.
- Like mammals, penguins don’t have true hair.
One of the prominent characteristics of mammals is having true hair. Nearly all mammals possess true hair. Then we should note that penguins don’t have true hair. Apparently, their skin gives the impression of fur but actually covered with closely packed feathers. This character of penguins belongs to birds and not to mammals. The feathers provide protection and insulation against cold and wet atmosphere s. Unlike other birds, they have waterproof feathers. Two layers of feathers are present. The outer layer has an oily texture that prevents entry of water and the inner layer has trapped air which keeps them warm.
- Penguins have feathers like birds.
Penguins possess feathers like birds although they cannot fly. They are flightless birds like ostrich and peacock. They have adapted themselves in their evolutionary history for living on land and water. Throughout their history, they don’t have much fear of flying away from their predators. They had nothing to fly away from. So they didn’t feel any need to fly actively. This adaptation reduced their wings. Instead, they developed flippers for swimming in oceans and they can swim and dive very easily in water… Why do they start swimming? The answer is that they had to rely on seafood, so they learned to dive inside the water and to swim fast in order to reach their prey more effectively.
- Penguins lay eggs like birds.
Penguins lay eggs with hard shells like birds. This is a very distinct feature of birds. Male penguins provide incubation for around 65 days and he even didn’t care about eating his own food properly these days. This feature of penguins allows us to consider them as birds.
- Penguins have hollow bones like birds.
Penguins have porous, almost hollow and less dense bones. This feature again relates to birds. Birds have light bones and this makes it easier for them to fly. Although penguins are flightless birds, they still have porous bones which shows that they are actually birds.
- Penguins have a four-chambered heart like birds and mammals.
All the mammals and birds have a four-chambered heart. Penguins also have two atria and two ventricles for complete oxygenation and deoxygenation of blood. But like birds, their heart sizes are also slightly modified. They have a faster heart rate and slightly large hearts. So their heart structure and function is more closely resembles birds. This cannot be the distinguishing feature.
- Penguins have feet instead of paws or legs of mammals.
Penguins do not have paws or legs (although they have knees) like mammals, but they have feet like birds. Their motion in water more closely resembles flying rather than swimming motion used by other animals.
- Penguins produce sounds through syrinx like birds.
Penguins produce sounds through syrinx, which is the organ unique to birds, that’s why they have shrilling and piercing sound. The size of the syrinx is even smaller than the raindrop. When the chick wants food, it peeps and wags it and produces shrilling sound using syrinx. There is no concept of the syrinx in mammals. They can never have such a very tiny structure for making a sound because they have comparably high-level voices. We know that mammals produce sounds through the larynx. This feature is another evidence that penguins are not mammals.
- Penguins are not amphibians, reptiles or fish.
They are neither amphibians nor fish. Unlike fishes, they don’t have gills, they breathe air, they have feet, they are warm-blooded and they are actually the predators of fish. They can swim but this doesn’t show that they are fish. Many other birds and animals can swim. They are also not amphibians because they do not live in water as a choice but they have to do it to get their food. As we know they depend on seafood. They are unable to fly so seafood is the most available form of food for these creatures. So they adapted themselves for a wet environment although they are birds in all other ways.
Penguins are not mammals. They are birds because they possess all the features of birds. They are birds of the family Spheniscidae and subclass Impennes. They have all features of birds like feathers, light bones, egg-laying ability, lifestyle, feeding manners of young ones, etc. Their behavior is basically so difficult to analyze because sometimes they resemble amphibians and sometimes to mammals but we cannot completely rely on our senses but we have to focus on scientific evidence. All the evidence has proved that they are the birds.
For further information, I want to add the importance of penguins in our lives which can be understood from the fact that Penguin days are celebrated twice a year. 20th January is Penguin Awareness Day and 25th April is World’s Penguin Day.