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.
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
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.
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
|If your pet is a tiger salamander, the transition into a full-fledged
salamander is a natural part of its development into a mature adult. However
when axolotls make this transformation, it's usually in reaction to a significant
change in their environment like increased water toxicity or reduced water
levels. If you don't know what your pet is, you won't know whether your
pet is changing for good reasons or bad. |
|Some symptoms of illness resemble harmless changes that are part of
the metamorphic process. For example, shrinking gills, change in appetite,
and increased amounts of lethargy and time spent at the water's surface
are all characteristic of metamorphosis. But all of those symptoms can
also happen to axolotls or juvenile tiger salamanders as a result of illness.You
will be able to diagnose problems more quickly if you know whether to expect
these changes. Again, it's normal for tiger salamanders to do it, but axolotls
do it only when conditions make it necessary for survival. |
|If you have an axolotl that begins to metamorphose in response to a
problem, you can often reverse the process by fixing the problem in time.
This is good, because axolotls live longer and are much more active in
their neotenous form. But if you start making changes to a tiger salamander's
environment while it's trying to change, you can seriously make things
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.
- 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.
- 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
- 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.
- 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.
- 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.
- 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
- 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.
Above: A juvenile tiger salamander.
Above: A mature tiger salamander.
Above: Two mature white axolotls.
Above: A real mudpuppy.
Below: A mature white axolotl after
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