As mammals and amphibians are both animals and part of the kingdom Animalia, they share many similarities. However, there are also many differences between the two.
Mammals give birth to live young, whereas amphibians’ delivery occurs externally. Mammals are warm-blooded, while amphibians are cold-blooded. Mammals can live in all habitats and have muted colors, unlike amphibians. Some amphibians can regenerate their limbs.
If you want to read more about the differences and similarities between both groups of animals, please read on.
There are many classes of animals in the natural world, and one that is often overlooked is the amphibian. They are a strange class of newts, frogs, toads, and salamanders.
Some may mistake them for reptiles because their appearance is similar to lizards. But, they are a class all of their own. So what similarities do mammals share with these creatures, if any? What clever adaptations and differences set mammals and amphibians apart?
What Are The Similarities Between Mammals And Amphibians?
Mammals and amphibians are both vertebrates. This means they both have a similar skeletal system with a backbone and a central nervous system.
By comparison, insects, mollusks, and arthropods are invertebrates because there is no backbone. While this might come as a surprise when you see something like a newt swimming around in a pond, they have spines with tiny vertebrae, just like us.
Amphibians are semi-aquatic and can survive on land out of the water for short periods. They do so by breathing air into their lungs as a mammal does.
Amphibians can also absorb oxygen and water through their skin because it is much more porous. If amphibians were to stay out of the water for too long, they would suffer from dehydration.
Many amphibians hibernate to survive the cold winter. This is something you also see with some mammals living in colder climates and is a common survival strategy. There are, however, some differences in the details.
Not all mammals shut down in a profound lethargy the same way as amphibians. Some mammals will periodically wake. Mammals will also build fat reserves and larders to help them through the winter.
The metabolism of frogs, toads, and newts can shut down significantly during this time. They need to be sure that they are in the right conditions. Terrestrial frogs should be safe in caves, but aquatic frogs must contact oxygen-rich water as they hibernate in the mud.
From there, there are a lot more differences between mammals and amphibians. Some are pretty drastic, and others are a little more subtle.
What Are The Differences Between Mammals And Amphibians?
Development And Birth
You will see that almost all mammals keep their young inside their reproductive system until it is time to give birth. The length of this pregnancy differs depending on the animals and the complexity of their physiology.
The embryos develop into fetuses and then are born as baby animals that can survive, with supervision and feeding, and function independently.
With amphibians, the process of development takes place externally. Let’s use frogs as an example. Males will fertilize a female’s eggs during mating, which she will deposit as clumps of spawn. Over time, the embryos develop without any additional influence from the parents. They turn into tadpoles and feed on their own, then into froglets, losing their tails and becoming mature frogs.
Again, there are some cases in the mammalian world where animals do things differently.
One such example is the kangaroo, which is a marsupial. Here the fetus develops in a pouch on the mother’s stomach where it can gain the nutrients it needs via her. It then grows into a joey and eventually becomes independent enough to leave the pouch, although it can return for protection, warmth, feeding, and transportation.
There is a small group of egg-laying mammals. These monotremes are still mammals, even though they don’t give birth to live young in the same way. They still have mammary glands producing milk and many other classic features.
Cold-blooded And Warm-blooded
Another key difference is that mammals are warm-blooded creatures, while amphibians are cold-blooded. This means that mammals can regulate their body to stay at around the same temperature all the time. This is something that we do ourselves.
When we are too hot, we head for shade so that the cool external temperature cools our blood. That is why it helps when we put ice on the veins in our wrists. The vessels are so close to the surface that the blood cools and subsequently cools other parts of the body.
Some animals in hot climates have large ears with extensive surface areas for the same reason. Mammals can also sweat and pant when hot.
We can retreat to warmer places to heat up or shiver to generate energy when it is too cold. Animals with fur often have denser coats in colder climates for insulation.
Some creatures will also have shorter legs, muzzles, and smaller extremities to control blood flow. It is thought that the snub-nosed monkey evolved without its nose to evade frostbite.
Amphibians are cold-blooded, so they take on the temperature of the habitat around them. They can get sluggish when things get too cold and won’t move much. This could be a problem if they haven’t eaten in a while. This is one of the reasons for hibernation in winter. Moving to a sunnier spot will warm them up and help them get the energy they need.
One of the obvious traits of mammals is their ability to adapt to almost any environment and climate globally. We find mammals living in forests, deserts, polar regions, and everywhere in between because there are so many different species with such varied adaptations.
The cold-blooded nature of the amphibians, and their reliance on water, means that they cannot colonize so many habitats and regions. Temperate zones with plenty of freshwater pools offer excellent habitats for frogs, toads, and newts. Beavers can play an essential part in habitat management for frogs by creating still collections via their dams.
The colors on the porous skin of amphibians can vary dramatically. While many toads have darker skin to blend in with their surroundings, many frog species have an array of colors and patterns.
Some frogs have green coloration with spots to break up their shape. This is important for camouflage against leaves and pondweed. While there are no green mammals, they often use color for this purpose as they remain hidden in their habitat.
However, you never see any mammals with brightly colored fur in blue or bright yellow tones. Their patterns also tend to be more simple.
By comparison, poison dart frogs in the rainforest are vivid and stand out quickly. The purpose here is to show predators that they aren’t edible.
Of course, there always has to be a species that plays by its own rules. The glass frog is an excellent example because it is transparent on its body. Scientists still debate why this is the case.
There are lots of stories about the incredible powers of the salamander. Some people say they are immune to fire, while others suggest they will actively put out fires if they see them.
It is undeniably true about salamanders that they, like some lizard species, can regenerate limbs and parts of their tail. If they are ever caught by predators or injured, they can detach the tail or limb, leave that wriggling in the predator’s mouth, and flee. A new stem then grows, and they can get on with their life as usual. They do so due to macrophage cells, which are incredibly effective in healing.
Another amphibian is the olm. This form of salamander has adapted to live in cave systems in central Europe. Its evolution in these dark spaces means it has become blind, as it has no use for eyesight. It is also thought that they can live as old as 100.
There are similarities here to mammals, such as moles and other subterranean creatures. They, too, have little use for sight to hunt for their food. However, they can’t survive anywhere near as long as an olm.
Amphibians and mammals may be vertebrates but branch off in very different directions.
The distinction between vertebrates and invertebrates is important when classifying the animal world, but that is the start of the differences here.
It isn’t uncommon to see amphibians and mammals sharing habitats in temperate and tropical zones, but they do so with very different traits. The reproductive cycles and regenerative powers are the most striking. The difference in their blood temperatures drastically affects where they live and how they survive the winter. Although mammals and amphibians have a backbone, there are many differences between them.
Bryan Harding is a member of the American Society of Mammalogists and a member of the American Birding Association. Bryan is especially fond of mammals and has studied and worked with them around the world. Bryan serves as owner, writer, and publisher of North American Nature.