Amphibians have evolved about 365M years ago from a lobe-finned lungfish ancestor. They are considered to be the earliest land vertebrates, and this fact allowed them to strive. They were the dominant land vertebrates for more than a 100M years (but then pesky reptiles evolved from them, taking their crown as the kings of vertebrates)!

Fun (and Other) Facts

• Undergo Metamorphosis

  Amphibians Undergo Metamorphosis

  True to their evolutionary position halfway between fish and fully terrestrial vertebrates, most amphibians hatch from eggs laid in water and briefly pursue a fully marine lifestyle, complete with external gills. These larvae then undergo a metamorphosis in which they lose their tails, shed their gills, grow sturdy legs, and develop primitive lungs, at which point they can scramble up onto dry land.

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• Must Live Near Water

  Amphibians Must Live Near Water

  The word "amphibian" is Greek for "both kinds of life," and that pretty much sums up what makes these vertebrates special: they have to lay their eggs in the water and require a steady supply of moisture in order to survive.

  To put it a bit more plainly, amphibians are perched midway on the evolutionary tree between fish, which lead a fully marine lifestyle, and reptiles and mammals, which are fully terrestrial and either lay their eggs on dry land or give birth to live young. Amphibians may be found in a variety of habitats near or in water or damp areas, such as streams, bogs, swamps, forests, meadows, and rainforests.

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• Permeable Skin

  Permeable Skin

  Part of the reason amphibians have to stay in or near bodies of water is that they have thin, water-permeable skin; if these animals ventured too far inland, they would literally dry up and die.

  To help keep their skin moist, amphibians are constantly secreting mucous (hence the reputation of frogs and salamanders as "slimy" creatures), and their dermis is also studded with glands that produce noxious chemicals, meant to deter predators. In most species, these toxins are barely noticeable, but some frogs are sufficiently poisonous to kill a full-grown human being.

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• Have Extremely Primitive Lungs & Skin Surface Respiration

  Primitive Lungs & Skin Respiration

  Much of the progress in vertebrate evolution goes hand-in-hand (or alveolus-in-alveolus) with the efficiency of a given species' lungs. By this reckoning, amphibians are positioned near the bottom of the oxygen-breathing ladder: Their lungs have a relatively low internal volume, and can't process nearly as much air as the lungs of reptiles and mammals.

  Fortunately, amphibians can also absorb limited amounts of oxygen through their moist, permeable skin, thus enabling them, just barely, to fulfill their metabolic needs.

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• Are Among World's Most Endangered Animals

  Amphibians are Among the World's Most Endangered Animals!

  With their small size, permeable skins and dependence on easily accessible bodies of water, amphibians are more vulnerable than most other animals to endangerment and extinction; it's believed that half of all the world's amphibian species are directly threatened by pollution, habitat destruction, invasive species, and even the erosion of the ozone layer.

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• Double-channeled Hearing System
• Cold-Blooded

  Amphibians are Cold-Blooded

  Warm-blooded metabolisms are usually associated with more "advanced" vertebrates, so it's no surprise that amphibians are strictly ectothermic—they heat up, and cool down according to the ambient temperature of the surrounding environment.

  This is good news in that warm-blooded animals have to eat much more food to maintain their internal body temperature, but it's bad news in that amphibians are extremely limited in the ecosystems in which they can thrive in—a few degrees too hot, or a few degrees too cold, and they will immediately perish

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Frogs&Toads

Though the first amphibian, Ichthyostega, looked more like a salamander, than a frog, today frogs are the most numerous amphibians. We all probably agree that Toads and Frogs are pretty similar (they are even from the same order Anura of the class Amphibia), but have you ever wondered what is the difference? Some of you may know the difference, or even feel it, but have thou CLASSIFIED IT?

How to Tell a Frog and a Toad Apart?!

Settling a debate Congress theoretically could rant about for 3 years (or more) Toads are FROGS! Haha! Got you! Didn't expect this turn of events, did you? Well, actually toads are a "are a sub-classification of frogs," so we still have to know how to tell them apart. As I already mentioned, both frogs and toads are a part of the order Anura (which translates to "without a tail"). This order, among others, has two families: Ranidae (referred to as "true frogs") and Bufonidae (referred to as — you guessed it — "true toads"). Excited to know the difference? Behold! I compared (actually, just Googled, but we will not mention it) these families for you:

Now that you know the differences, let's test you in an exciting game I called: Frog or Toad?

Frog or Toad?

Frog Toad

Origins

How dare you call yourself a frog fan without knowing how frogs appeared — I asked myself one day. And you should ask this question too. Curiosity is the key to success, survival and life, you know. Turns out there is an excellent presentation on Google's Arts&Culture Website by someone named Frogs&Friends called "The First Leap". You a 100% have to open it up. It is nice and short. But, in short, 290M years ago a frogmander (half-frog, half-salamander) Gerobatrachus appeared. Then, 250M years ago the first frog Triadobatrachus massinoti has appeared!

Habitat

In short, they live on every continent, except Antarctica. Which is good, unless you don't like Frogs. In which case you should go to Antarctica because WHAT IS WRONG WITH YOU?!

Wood Frog Appreciation Stand

Honestly, Wood Frogs have earned the spotlight. They are the only frogs that live North of the arctic circle. They're so tough they should be mentioned on the Joe Rogan's podcast along with polar bears. Here, just read more about them.

In long, here's the "Frogality Map" which I "borrowed" from this website.

This map clearly shows that there are a lot of frogs. It also shows that you should move to South America because it has the largest number of our favorite frogs. But why are there so many frogs in this specific region? Perhaps, if we were to figure out the conditions that our frog friends liked, we could have set up an elaborate chain of lobbying and propaganda that would create global climate crisis and undermine its effects in order to make the world climate suitable for our frog friends to OCCUPY ThE ENTIRE WORLD!

In reality, frogs and toads are so diverse that some prefer cold and some prefer hot environments. It is just so happened that there are a lot of frog species in the tropics, due to favorable rich-in-nutrients conditions. Remember! By changing the environment you'll be destroying the habitat of the frogs living at the extremes, so just don't change the environment. Save the wood frog!

Besides the environment, frogs need a place to hide and a place to breed. For the former, they prefer a cool and moist place, sheltered from weather and predators. For the latter, most require a "permanent source of moisture" such as a pond, dam or river (though it differs from frog to frog).

Food

Frogs eat insects such as flies and moths, as well as snails, slugs and worms. They use long tongues and sticky saliva to catch prey that passes them by (Rachel Hoskins). Tadpoles eat algae in the ponds they grow in (Rachel Hoskins). As they grow, they feed on plants and small insects (Rachel Hoskins). If there isn't enough food available they might even eat their fellow tadpoles (Rachel Hoskins).

Salamanders

Don't Call It a Lizard!

Salamanders are, in fact, not lizards! They have similarities such as slender bodies, short legs and long tails, but THEY ARE NOT THE SAME! This is why, again, just like with frogs and toads, I compiled a table to contrast them in order for an uneducated public (including myself, until recently) to engrave the difference in their heads.

Now, prove to me you're worthy of being a salamander expert in a game "Salamander or Lizard?"

Salamander or Lizard?

Salamander Lizard

Habitat

What you should have picked up from our discussion so far is that amphibians looooove water. Salamanders, being Amphibians, duh, are not an exception. They live in moist or arid habitats in the northern hemisphere (mostly Americas), most salamanders are small, although there are two species that reach up to 5ft (1.5m) in length! Those lizard (but not lizard) like creatures live near water or shelter in the moist ground: brooks, creeks, ponds, and other moist locations such as under rocks. They lay (shell-less) eggs in water, so they need clean water! Hence, don't pollute water!!!

Axolotl Hall of Fame

People love axolotls. Yes, this is a statement and a true fact based on personal experience, mostly. They're famous as, unlike regular salamanders, they can reach adulthood without undergoing metamorphosis, hereby remaining aquatic and gilled. Oh, they also can regenerate, much like all salamanders. But it is not for the love that they have the spotlight, it is because we owe them a serious apology. And I literally cannot underscore the extent of this apology enough. Their original habitat is in the lakes near this something we now call Mexico City. When the settlers came to colonize, they drained the Axolotls' lakes, destroying much of their original habitat. But, as much as I desire to finish this, the awfulness does not end on that note. In 2020 axolotls had to bear near extinction because we, selfish humans, decided to pollute the homes of axolotls for the sake of our concrete homes. So... Give your Respect to an Axolotl when you see one!

Food

Much like frogs, you should say a big thanks to salamanders for eatings all these insects you hate, such as larvae of mosquitos, and flies. They also save us from worms, crickets, centipedes and spiders. Additionally, some salamanders eat other small invertebrates.

Regeneration

Salamanders are well-know for their regenerational powers! I wish I could grow, let's say, a leg... Imagine how much you could save on hospital bills if you had this kind of power? Forgot to bring a snack with you to a day-long hike? Lend yourself your helping hand!

Caecilians

What... Even is this thing?!

This was the first question I asked when i saw THIS. It looks as if a worm and an electric eel had a baby! How can this be related to those cutesy frogs we have all seen above?! Well, turns out it can. Imagine a blind and long salamander without legs and with rings along their bodies (those that worms usually have). Imagined? Yeah... You get caecilians.

Origins

The natural question you may ask is where did evolution mess up so much in order to create this. Why would we even have that? Well, it certainly has advantages. Just like worms they dig tunnels, which is why they neither need sight, nor hearing. The earliest fossil attributed to a stem-caecilian (an amphibian closer to caecilians than to frogs or salamanders but not a member of the extant caecilian lineage) comes from the Jurassic period. Back then those things still had limbs (though small) and well-developed eyes. So, you could say, from human perspective caecilians have devolved.

Habitat

Turns out, they live in a lot of places: ranging from Central Africa, Southeast Asia, and southern Mexico to Argentina, these creatures prefer loose soil and leaf litter in tropical forests or near rivers and streams.

Food

Unlike worms, this thing has a sharp tooth. Sharp indeed. It has two rows on the upper jaw and one or two on the lower. The teeth allow them to grab worms, termites, beetle pupae, mollusks, small snakes, frogs, lizards, and even other caecilians! All food is swallowed whole. Furthermore, caecilians have toxic glands in their skin that sometimes protect them from being eaten by other wildlife.