Random Amphibian Generator

What the amphibian generator does

So you want a random amphibian. For a quiz, a class, a game, a writing prompt, or just to see what turns up.

This gives you one. Frogs, toads, newts, salamanders, and the strange things that are none of the above.

Then read on. Because there is one fact about amphibians that explains almost everything else about them, including the very bad thing that has been happening to them for the last forty years, and it is a fact about their skin.

How to use it

Press Generate for one, or a batch to read down, then Copy to keep them.

An amphibian breathes through its skin, and that is the problem

The word is Greek. Amphibios. Both lives. It is about the water and the land, the tadpole and the frog, the animal that does the whole thing twice.

But the thing that actually makes an amphibian an amphibian is not the two lives. It is the skin.

Your skin is a wall. That is its job. It keeps the inside in and the outside out, and it is very good at it.

An amphibian's skin is not a wall. It is a membrane, and it is permeable on purpose, because it is doing work. Oxygen comes in through it. Carbon dioxide goes out through it. Water crosses it. Salts cross it. A lot of amphibians can get most of the oxygen they need through their skin alone, and some salamanders have given up on lungs entirely and just breathe through their body surface, all day, every day, for their whole lives.

So an amphibian is not a small animal wearing skin. It is a small animal that is partly made of gills, arranged in the shape of a coat.

Which is wonderful, and which is why they have to stay damp, and why they cannot live in salt water, and why they are the first thing to go when a pond gets polluted, and why biologists watch them the way miners watched canaries. If it is in the water, it is in the frog. There is nothing in between.

And it is why the thing in the next section was able to do what it did.

Because if your skin is your lungs and half your kidneys, then anything that attacks your skin is not attacking your skin.

The worst thing a disease has ever done

In 2019 a team of researchers published a paper in Science with a title that does not oversell it. Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity.

The subject is a fungus. Batrachochytrium dendrobatidis, which everybody calls Bd because life is short. It is a chytrid fungus, an ancient and mostly unremarkable group, and this particular one eats keratin, which is the stuff in amphibian skin.

It gets into the skin. It thickens it. And a thickened skin on an animal that breathes and balances its salts through its skin is not a rash. The electrolytes go wrong. The heart stops.

The fungus does not poison the frog. It simply makes the frog's skin behave like ours, and that is enough.

Here is what the paper found. Bd is implicated in the decline of at least 501 amphibian species over about half a century, including 90 presumed extinct. Declines peaked in the 1980s. Of the species that crashed, only around 12 percent show any sign of recovery, while 39 percent are still going down.

Their summary sentence is the one that gets quoted, and it earns it: this is the greatest recorded loss of biodiversity attributable to a disease.

Not the greatest for amphibians. The greatest, full stop, for anything, from any disease we know about.

And then there is the detail that tells you how it happened. Bd has caused declines everywhere on Earth except one place: Asia, where it appears to have come from. Which is what an introduced pathogen looks like. Where it is native, the local amphibians have lived alongside it for a very long time and are largely fine. Everywhere else, it arrived on something. Trade, in other words. We moved animals around, and the fungus went with them, and it met a few thousand species that had never had to survive it.

Two of the ones that are gone are worth saying out loud.

The golden toad. Bright orange, lived in one cloud forest in Costa Rica, and now lives nowhere.

And the gastric brooding frog, which is the one that keeps me up. It swallowed its own fertilised eggs. It shut down its stomach acid, grew its young inside its own gut, and then gave birth through its mouth. Nothing else on Earth does that. It was discovered in the 1970s and it was gone within about a decade. We found it, we worked out what it was doing, and then it stopped existing while people were still writing papers about it.

What the scientists are still arguing about

Now the honest part, because a page that quotes one number and stops is not telling you what is actually going on.

That 501 figure got challenged. In print, in Science, by other amphibian researchers.

Their argument was not that chytrid is harmless. Nobody thinks that. Their argument was about the evidence for each individual species on the list. The 501 came from an expert-curated assessment, and the critics went through it and said that for a lot of those species the link between the fungus and the decline is not solidly established. Which species, and how many, they said, is still an open question. And getting it wrong matters, because conservation money follows the numbers.

The original authors responded. The argument is still there in the literature, and anybody can read both halves.

I am telling you this because it is the interesting bit, not despite it being awkward. This is what a real scientific finding looks like from the inside. Not a fact handed down. A very large claim, made carefully, then picked at hard by people who agree with the general point and want the specifics to hold up.

And notice what nobody is arguing about. Chytridiomycosis is unambiguously implicated in amphibian declines. That sentence is from the critics. Both sides agree the fungus is a catastrophe. Both sides agree that somewhere north of 40 percent of amphibian species are facing extinction, which makes them the most threatened class of vertebrates on the planet.

They are arguing about how to count the bodies. Not about whether there are bodies.

Taking an amphibian apart

The list has frogs, toads, newts and salamanders in it, and those four words are doing less than you think.

Start with the split that is real. There are three orders of living amphibian.

Anurans are frogs and toads. The name means tail-less, which is exactly what they are as adults, and it is the whole design: no tail, long back legs, built for jumping. This is most amphibians by a wide margin.

Caudates are salamanders and newts. Tailed. Four legs of roughly equal length, and a body that is basically a lizard shape that never went in for scales.

Caecilians are the third order and almost nobody has heard of them. They are legless. They live underground. They look like large earthworms and they are not remotely earthworms, they are amphibians with a skull and a spine, and there are a couple hundred species of them going about their business in the tropics while nobody watches.

Now the split that is not real.

Frog and toad is not a scientific distinction. There is no toad order. Toad is a shape: warty, dry-looking, short-legged, walks more than it jumps. Plenty of animals called toads are sitting in frog families, and the word is doing folk taxonomy rather than biology.

Newt and salamander is the same trick. All newts are salamanders. Newt is a subgroup, and the word survives because English had it first and never gave it up.

So of the four words everyone knows, two are real orders and two are vibes.

The one that refused to grow up

The axolotl is in this list, and it breaks the definition of the thing it is.

The whole idea of an amphibian is the two lives. Larva in the water with gills, adult on the land with lungs. Metamorphosis is the hinge the entire group turns on.

The axolotl does not do it.

It hatches, it grows, it gets big, it becomes sexually mature, it reproduces, and it dies, all without ever metamorphosing. It keeps the gills. It keeps the tail fin. It stays in the water. An adult axolotl is, structurally, a larva that got large and started having children.

Biologists call it neoteny. The animal called the double-lifed one has one life and it is the first one.

And there is a second thing about it, which is why it is in laboratories all over the world. An axolotl can regrow a leg. Not scar over. Regrow. Bone, muscle, nerve, the lot, correctly. It can do the same with parts of its heart and its brain, which is why more or less everybody working on regeneration keeps a tank of them.

So here is the situation. The axolotl is one of the most common laboratory animals on Earth, sold in pet shops, drawn on stationery, made into a video game character, kept by the hundred thousand.

And in the wild it lives in the remains of one lake system on the edge of Mexico City, and there are almost none left. Surveys have gone out and come back with numbers you could count on your hands.

An animal that is everywhere and nowhere at the same time. Millions of them alive, and functionally none of them at home.

How this list was made

Nothing clever.

It is a curated list, checked by a person rather than scraped, using the common names people actually use. Generate pulls at random from the list, and you get no duplicates in a batch.

It all happens locally, on your own machine, and none of it is sent anywhere.

Questions people ask

What is the difference between a frog and a toad?

Nothing official. They are all in the same order. Toad describes a look, warty and dry and short-legged, and the word gets applied across several unrelated families. It is a real distinction to your eyes and not one to a taxonomist.

Is a newt a salamander?

Yes. All newts are salamanders, in the same way all robins are birds. Newt is a subgroup that English happened to have its own word for.

Are amphibians reptiles?

No, and the skin is the giveaway. A reptile is sealed: scales, waterproof, lays an egg with a shell that holds its own water. An amphibian is open to the world at every point, and usually has to put its eggs in water because they have no shell to keep them from drying out.

Is it bad to pick up a frog?

Generally, yes. Their skin is doing the breathing, so anything on your hands goes straight in, and the oils and salts on human skin are not good for them. And, more seriously, chytrid moves on contact and on wet gear. Anyone working with wild amphibians disinfects between sites for exactly this reason.

Is the axolotl extinct?

Not as a species, and almost entirely as a wild animal. There are enormous numbers in captivity and there are next to none left in the lake system near Mexico City where it comes from. It is the strangest conservation status there is: safe forever, and nearly gone.

Why do people care so much about frogs specifically?

Partly the permeable skin, which makes them an early warning system for whatever is in the water. Partly the scale of what has already happened, which is the largest disease-driven loss of wildlife ever recorded. And partly that they have been here for something like 350 million years, through several mass extinctions, and are having their worst time on record during ours.

References

1. Scheele, B. C. et al. (2019). Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity. Science, 363(6434), 1459 to 1463. https://doi.org/10.1126/science.aav0379
2. Comment on "Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity". Science. https://doi.org/10.1126/science.aay1838
3. Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity. PubMed. https://pubmed.ncbi.nlm.nih.gov/30923224/
4. Deadly fungal disease has devastated more than 500 amphibian species. Mongabay, 1 April 2019. https://news.mongabay.com/2019/04/deadly-fungal-disease-has-devastated-more-than-500-amphibian-species/