Axolotl Or Salamander?

How To Tell The Difference

Last updated March 18, 2000

I get at least one email a week from someone whose pet is losing its gills and spending a lot more time at the surface of the water, breathing air with its mouth or through its nostrils. Half of the people who write me about this assume that their axolotl is metamorphosing. The other half think their axolotl is getting sick. Almost none of them consider the possibility that their pet might not really be an axolotl. This confusion has many causes. I will address these first, and then I'll give you some tips on how to figure out what kind of creature you have.

Index

Pet shop terminology

In all the pet shops that I have ever been to over the years, I have only seen axolotls and tiger salamanders properly identified three times. Most of the time, axolotls or larval tiger salamanders are listed simply as "water dogs" or "mud puppies." Store employees who claim to have any knowledge of the animals at all will usually tell you that the mud puppies are still juveniles who will eventually lose their gills to become salamanders or "lizards."

Even though most axolotls stay under water and keep their gills for the rest of their lives, only rarely will a pet shop worker be aware of this fact. This is because tiger salamanders are generally more common in pet shops than axolotls (in the United States, at least) and salamanders are often shipped to the stores while they are still young, in their larval form.

The animals either die or are sold long before the folks at the pet shop have enough time to realize that some of these weird looking beasts never lose their gills.

Note
There is actually a species of salamander that occurs naturally in the southeastern United States and retains its gills for its entire life, called a mudpuppy. Interestingly, the mudpuppy is not related to tiger salamanders or axolotls and I have never seen a pet shop "mud puppy" that looked anything like the real thing! These animals are pretty rare in pet stores, but I've heard from lots of people around Mississippi and Louisiana who've found them literally in their own back yards.

Confusion over the word "axolotl"

A lot of people seem to think that "axolotl" is a word for the larval form of any salamander rather than the name of a certain species. This confusion probably has to do with the fact that young tiger salamanders look a whole lot like young axolotls. But they are not the same. When properly used, the word axolotl refers only to creatures belonging to the species Ambystoma mexicanum, that originated in the lakes of Mexico. The tiger salamander (Ambystoma tigrinum) is a closely related, but different, species.

I understand that some scientific types like to refer to larval salamanders as axolotls, simply because its quicker than saying "juvenile tiger salamander." While people who do this are normally aware that they are lumping different species together, this over-application of the term trickles down into mass confusion among the pet-owning public.

Does it really matter?

There are a number of important reasons to know what kind of animal you have:

Identifying your pet

First off, even experts who work with axolotls and tiger salamanders all the time have difficulty telling them apart when the animals are young. Here are a number of things to look for. No single one of these tips is a sure thing, but taking all of them into account should prove helpful.

1. Color: In the wild, axolotls tend to be dark gray to black, often with light or dark flecks of color throughout. Generations of lab work with axolotls has yielded many color variations within the species. At pet shops and medical livestock distributors you are likely to find axolotls with one or more of these colors: White, green, black, brown, or gray. White axolotls are not always albino (such was the case with my Puckles) but albinos are not uncommon. In contrast, tiger salamanders are normally some combination of green and yellow, often with some portions of black or dull brown.
2. Pattern: Tiger salamanders are more likely to have a somewhat uniform coloration pattern than axolotls. Some tiger salamanders have big yellow polka dots, while others have the eponymous yellow tiger stripes down their backs. Color seems to be more randomly distributed in axolotl populations.
3. Behavior: After metamorphosis, tiger salamanders are usually more aggressive and energetic than axolotls. I've heard from a few people who did have axolotls (mostly Biology students who were allowed to take their test subjects home) that underwent metamorphosis only to become somewhat dull and lethargic salamanders. This is not entirely a bad thing, though. Because they're so hyperactive, tiger salamanders are more likely to escape an aquarium than transformed axolotls. Always make sure that your tank's ventilated top doesn't have any holes that are big enough for a salamander to fit through.
4. Gills: One of my correspondents has observed that axolotls often flick their gills, while young tiger salamanders don't seem to do it much, if at all. So you might be able to say that if the animal never flicks its gills, it's probably not an axolotl- but if it does flick its gills that doesn't necessarily mean that it is an axolotl. The act of gill-flicking is a way to shake carbon dioxide off of them to make room for more incoming oxygen.
5. Girth: One thing I've noticed is that healthy tiger salamanders tend to me more slender than healthy axolotls. This can be a tough call to make in pet shops though, because most amphibians that I've seen in pet shops were underfed and uncharacteristically skinny anyway.
6. Piggies: I have heard, but not been able to personally confirm, that axolotl fingers and toes are longer and more slender than those of tiger salamanders. This might make sense for the axolotl because the long digits probably aid swimming, while they might get in the way if the axolotl had to get around on land regularly, like the tiger salamander. I have also heard that the back toes of tiger salamanders are flatter than those of axolotls.
7. Tail: Another tip that I have not been able to personally confirm has to do with the tail. On axolotls and young tigers, the ridge of the tail travels all the way up the back, tapering off gradually. Supposedly, this ridge, which reaches all the way to the back of an axolotl's head, only goes as far as a tiger salamander's neck.

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