Amphibians are vertebrates because they have a backbone. But that's one of only a few traits they share with humans. Amphibians are very odd creatures with some really unusual characteristics. They do things with their skin and eyes that look like superpowers.
You won't believe what some amphibians feed their babies and what others do when they lose a limb or an eye. Check out some fascinating facts about one of nature's smoothest-skinned creatures...
A Frog's Eyes Helps It Swallow Prey
When a person enjoys a good meal, he or she may close their eyes in appreciation. But when a frog eats, its eyes help it swallow the food. After a frog catches its prey, the eyeballs will retract into its head. This helps to push down the food so the frog can swallow it.
Frogs don't use their teeth for chewing. Instead, they use their teeth to keep the prey in their mouths. Their tongue is attached at the front of the mouth, so it needs its eyes to help them swallow.
Newts Can Regenerate Their Limbs & Eyeballs
If something happens to their limbs, organs, or tissues (including heart muscle), a newt will simply regrow it. They can even regenerate their eyes, according to the journal Nature. It would be very helpful if humans could do the same thing, yet they cannot.
Researchers have studied the phenomenon and are trying to determine whether this genetic trait is simply latent in all animals. But one thing that sets newts apart from humans is that their haploid genome is 10 times bigger than that of people.
Frogs Have Transparent Eyelids
Unlike humans, the eyelids of a frog's eyes are transparent. In fact, they have three eyelids (one on the top and one on the bottom, which are transparent) as well as a semi-transparent eyelid. These eyelids help protect the frogs' eyes when they are underwater and keeps them moist when they're on land.
The semi-transparent eyelid on the red-eyed tree frog is designed like tiger stripes. This camouflages the frog's bright red eyes but doesn't interfere with vision.
Some Newts Secrete A Powerful & Lethal Mucus
In order to protect themselves, newts use their coloring (often green, black, or brown) to hide from predators. Others are bright in color to indicate that they are toxic. They secrete a mucus that is poisonous. In fact, the neurotoxin is so lethal it can stop the signals from your brain that compel your heart to beat.
One study found that a rough-skinned newt has enough poison on its skin to wipe out as many as 25,000 mice. A man who ate a newt on a dare died within hours of consumption.
The World's Largest Amphibian Is A Salamander That Weighs 140 Pounds
The largest amphibian on the planet is the Chinese Giant Salamander. It's been around since the Jurassic Period, which was about 170 million years ago. These salamanders can weigh as much as 140 pounds and grow as long as six feet. They live underwater and do not have gills.
Like frogs, they absorb oxygen through their skin. Even though they were once revered by the Chinese, they are currently endangered. Some specimens sell for as much as $1,500 apiece.
Newts Are Carnivores
Newts may be quite cute, but if you get one for a pet be prepared to feed it some of its favorite snacks. And because they're carnivores, that means they enjoy eating slugs, worms, insects, amphibian eggs, and small invertebrates. And that's only part of their diet.
When they're in the water, newts consume tadpoles, shrimp, insect larvae, and mollusks. When a newt is just a baby, it will eat small shrimp and insect larva.
Caecilians Have Many Needle-Like Teeth, And The Babies Eat Their Mother's Skin
Caecilians live underground, and most people will never come into contact with one. They burrow through the soil using their long, streamlined bodies. They do not have any limbs and range in size from less than three inches to nearly five feet long.
What's interesting is that they have dozens of teeth in their mouths shaped like needles. They swallow their food whole and favor worms, termites, and other invertebrates, as well as small snakes, frogs, and lizards. However, baby caecilians peel off their mother's skin and eat it (it's known as "uterine milk). Yummy!
Amphibians Like Sunbathing
When you call a person cold-blooded, it means he or she is not emotionally connected. As for amphibians, they are truly cold-blooded. They share this trait with fish and reptiles. Unlike humans, an amphibian's body does not regulate its temperature.
Instead, amphibians must cool off and warm up using the environment around them. That's why you will often see them sunbathing. Humans, meanwhile, are warm-blooded. But, as we already established, they can "be" cold-blooded by acting deliberately mean or cruel to those around them.
Newts Can Lay Hundreds Of Eggs (But Only One At A Time)
A female newt can lay hundreds of eggs. According to National Geographic, the warty newt lays between 200 and 300 eggs. But there's a catch -- they only lay one at a time and leave them affixed to aquatic plants. In contrast, frogs lay eggs in bunches, and the eggs float to the water's surface.
Baby newts are called larva. They look like baby fish and have feathered external gills. Over a short period of time, they grow into their adult form, just like frogs.
The Largest Frog In The World Can Weigh Up To Seven Pounds & Whistles To Find A Mate
There is a species of frog known as the Goliath frog that can measure between 6.5 inches to over a foot long. It can weight between one and seven pounds, and it is the world's largest frog. These creatures reach their full size three months after birth. They do not have vocal sacs, so they communicate by whistling.
What makes them unusual is that the males are usually larger than the females, something that doesn't occur often among frogs. Goliath frogs live in the tropics and are endangered.
Newts Have Lived In Space
In the mid-'90s, astronauts analyzed the embryonic development of Japanese red-bellied newts in space over the course of two missions. A study, published in Biological Science in Space, revealed that female newts laid their eggs in orbit. Then the eggs were exposed to low gravity and other environmental conditions in space.
When the embryos were analyzed, scientists discovered that they did not differ from embryos that undergo the traditional process on earth. However, there were some pathological changes in some of the adults newts that survived and returned to earth.
A Frog's Bulging Eyes Helps It See In All Directions
One thing that sets frogs apart is their big, bulging eyes. They stick out of their head so that frogs can see in nearly all directions without moving their heads. Their eyes are set far apart on their faces and give them a near 360-degree view of their environment. This allows them to hide from potential predators or to attack prey.
And as we mentioned earlier, the third, semi-transparent eyelid allows them to see underwater. It covers their eye but lets them see when they're swimming.
Female Newts Sometimes Try To Mate With Each Other
Depending on the species, newts are either active during the day or at night. They all spend the majority of their time searching for food or chilling out in shady spots. When it comes to mating, male newts emit a powerful pheromone and then dance by swinging their tales in the air.
According to a 2013 study by a Brussels university, their pheromones are so strong and ever present, that even when a male isn't present some females will try to mate with one another.
Frogs Breathe Through Their Skin But...
Frogs hibernate in the mud and are able to breathe through their skin by absorbing oxygen in the water. That's why you may see a frog swimming in the water during winter -- it's looking to find good oxygen levels in the pond. Some frogs can even stop their hearts and breathing completely while hibernating.
Their high glucose levels enables them to do this, and it protects their vital organs. They wake up and warm up when the weather gets warmer.
...Frogs Can Still Drown
Even though a frog breathes through its skin, it can still drown. Frogs, like humans, have lungs (only they're quite a bit smaller). So, if their lungs fill with water, they can drown. Also, in order for a frog to breathe through its skin, their skin has to be moist. If it dries out, they won't be able to absorb oxygen.
Since they use their skin to absorb oxygen when they're hanging out underwater, they need an oxygen-rich environment. Otherwise, they will drown and die.
Frogs Do Not Drink Water, And Scientists Aren't Sure If They Sleep
Frogs don't drink water like humans and other animals do. Instead, they absorb water through their skin. There is an area on their body known as a "drinking patch." It is located on their stomach, near the thigh area. This trait is common among many types of amphibians.
It's unclear if frogs sleep. Scientists haven't done too much research on the sleeping patterns of frogs. While they do close their eyes, it's unclear whether they are actually sleeping.
Frogs Eat Their Own Skin
Remember that creepy kid in school who used to eat his own scabs? Well, frogs do that too (sort of). Every once in a while, a frog will shed its skin, which is common in most animals. However, instead of simply sloughing it off, a frog will push the shedded skin into its mouth and consume it.
They do this because the skin contains a lot of protein. It's the ultimate way to recycle, courtesy of nature. Waste not, want not.
At One Point, Amphibians Were The Most Dominant Creatures On Earth
From the Carboniferous period (about 350 million years ago) through the Permian period (about 250 million years ago), amphibians ruled the earth. They were our planet's dominant terrestrial animal. Eventually, they were replaced by reptiles that evolved from certain amphibious populations.
Some of these reptiles turned into dinosaurs, while others evolved into mammals. At one time, there was an amphibian known as the Eryops. It weighed 600 pounds and was six-feet-tall from head to foot.
There Are 6,000 Species Of Frogs & Toads On The Planet
There are three main types of amphibians: frogs and toads, salamanders and newts, and caecilians. The latter is an odd, worm-like vertebrate. There are around 6,000 species of frogs and toads on the planet and about 500 species of salamanders, 60 species of newts, and 200 species of caecilians.
All amphibians that are alive today are smooth-skinned and classified as lissamphibians. Amphibians can survive in both aquatic and terrestrial habitats, which makes them a bit more versatile than humans.
The Oldest Living Amphibian Survived For Seven Decades
The olm (Proteus anguinus) is considered the world's longest-living amphibian. It was a salamander that lived in captivity for over 70 years. However, they may have a lifespan of over 100 years. There have also been other examples of old amphibians. One Salamandra lived for 50 years in captivity, and an Andrias japonicus lived for 55 years.
Some salamanders live at very high elevations. One, the Pseudoeurycea gadovii, lives above 5,000 meters on the volcano Pico de Orizaba in Mexico.