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All squeak, no bite: The common mudpuppy

Friday, June 26

Gills outside the body, a flat head and a propensity to eat anything it can fit in its mouth. It sounds like a description of an alien species, does it not? Luckily for us, this isn’t the work of H.G Wells, and these creatures aren’t going to attack us with heat-rays or spread red weeds everywhere. This description is of a mudpuppy, and true to its name, it’s an adorable lake-loving creature found here in the Midwest. It’s not a dog, it can’t bark, and it doesn’t enjoy a good tummy rub, but this rare and majestic salamander is wonderfully unique and captivatingly cute.

Unfortunately, mudpuppies are becoming very rare in our area. In fact, there have been no confirmed sightings (though many rumors or mentions) in decades. Even though they’re understated (and often underappreciated), mudpuppies are worthy of a little attention. Read on to learn about their weird, wonderful traits!

What is a mudpuppy?

Before anything else, we need to state the obvious: mudpuppies aren’t puppies; they’re salamanders. Mudpuppies (Necturus maculosus) are larger salamanders, usually just over a foot long, and are generally a rusty brown or grey color. They don’t go through full metamorphosis like most amphibians do. Metamorphosis is when an animal’s body changes at a certain age from a juvenile form to an adult form, usually fairly rapidly (in terms of body development, at least). Frogs, for example, hatch from an egg as a tadpole and then undergo metamorphosis some time later, growing legs and lungs while losing their tail and gills. Another classic example is the hungry caterpillar, which not only undergoes metamorphosis to turn into a pupa and afterwards a butterfly (or moth), but also (according to the children’s book) has a very similar diet to me. Mudpuppies are fairly unique among salamanders in that they don’t do any of that. They don’t undergo some massive body change or transition from juvenile to adult. They simply grow.

The most noticeable effect of not undergoing metamorphosis, in the mudpuppy’s case, is the huge set of feather dusters on its head. These are used for cleaning, as the mudpuppy is an extreme clean freak-

(That’s not what they are for? Oh. Let me try again.)

The most interesting feature resulting from a lack of metamorphosis is the set of party streamers sprouting from the mudpuppy’s ears. Mudpuppies are the definition of “party animal,” so much so that their enthusiasm manifested in-

(Not that either? Are you sure? I was pretty confident on that one.)

The most magnificent result of the mudpuppy’s lack of metamorphosis is its fleshy antlers. Commonly known as the river reindeer-

(Okay, okay, that’s the end of that joke, I’ll stop now.)

All jokes aside, the first thing most people notice about the mudpuppy are the prominent gills where ears would normally go. These frilly plumes are made of filaments containing blood vessels, and they work the same way lungs do. Mudpuppies pump blood through the gills and as the blood moves through the gills, it picks up all of the oxygen in the nearby water, just as lungs take up oxygen from the air. In fact, this is almost exactly the way fish gills work, except that the gills are outside the body, so the mudpuppy depends on the water’s current or moving around the water to continue to have fresh oxygen. This is also why they live in the water their entire lives; even though there’s more oxygen in the air than in water, gills are designed to efficiently capture whatever oxygen is available in the lakes and streams.

What do mudpuppies eat?

N. maculosus eat most anything that moves and that they can fit in their mouths. This includes small invertebrates like insects, worms and spiders as well as small fish, crayfish, snails and sometimes even other amphibians. Some research even shows that the mudpuppy may even forage and consume zebra mussels! They have an attached jawbone, however, which means they can’t eat larger prey.

Where do mudpuppies live?

Mudpuppies like to hide. They make their homes in holes under rocks, logs or other things they can burrow under. In fact, that’s why their head is flat and spade-shaped; it makes burrowing into the sand or gravel under rocks easy! They like the cool, deeper water of lakes but also visit shallower areas where plenty of dissolved oxygen is present. They sometimes live in streams, too.

Why are mudpuppies important? Why can’t we find them?

Before we talk about why they’re hard to find, let’s discuss just two of the many reasons why mudpuppies are an important ecological resource.

Mudpuppies have permeable skin, meaning some chemicals (for example, oxygen) can pass through their skin into their bloodstream. This makes them, and many other amphibians, very sensitive to water pollution, and even more so because they live exclusively in the water. Thus they’re considered bioindicators, species whose presence means there isn’t much pollution and the ecosystem is generally healthy and diverse. The other reason (definitely not the only other reason, but this article can only be so long) is that they help other species native to their territory. One in particular is the salamander mussel, a mussel whose larvae depend on the mudpuppy’s frilly facial features to be spread.

Mudpuppies are native to Indiana, but unfortunately their populations have shrunken drastically in recent history. That’s why they tend to be hard to find.

First, loss of habitat is a big factor in the missing mudpuppy mystery. They don’t like to live in silty or mucky streams, as the fine particles makes it harder for them to get oxygen. Second, as we mentioned earlier, they’re bioindicators. Their absence indicates that perhaps there is too much pollution. They need very clean water. And just like Dr. Seuss’s Humming Fish, whose gills were all gummed, the mudpuppies have hidden, in hopes of finding water that isn’t so smeary.

But that doesn’t mean they won’t come back! Due to the hard work of many in Kosciusko County, including the Lilly Center, water quality and habitats are being restored and protected. Hopefully, we’ll soon have confirmed reports of mudpuppies back in their ancestral homes once again!

Mudpuppy. Not an Axolotl, nor Hellbender, nor Tiger Salamander Larva.

Mudpuppies have a few doppelgangers. The most notorious look-alike is the ever-popular axolotl. The axolotl is another type of salamander that doesn’t do metamorphosis, and as such it has external gills just like the mudpuppy. They aren’t related, however. First and foremost, they’re from two very different areas; the axolotl is from Central America and couldn’t survive in Indiana’s colder climate, and the mudpuppy couldn’t deal with the heat that axolotls thrive in. Taxonomically speaking, they are in the same order (the order Urodela), but all that means is that they’re both salamanders. By that same logic, they’re about as far apart as buffalo are from giraffes.

Mudpuppies are also confused with a cousin of the axolotl, the larvae of the tiger salamander. Again, the resemblance is striking, however the tiger salamander larvae is just what it sounds like: a larva. Unlike mudpuppies, tiger salamander larvae will undergo metamorphosis and will lose their gills.

Last on the list of Salamanders That Aren’t Mudpuppies are hellbenders. Hellbenders are, in fact, native to Indiana (only the southern parts) but they don’t look much alike. Hellbenders are very large salamanders, growing up to three feet long, and don’t have external gills. They also aren’t related to mudpuppies, at least not closely.

The most important question: do mudpuppies bark?

There is a common myth about mudpuppies, often equating the “puppy” part of “mudpuppy” to the belief that they make a barking noise when out of water. Whether they do or not is generally a mystery, and various sources say different, opposite things. Some say that they make a squeaking or squealing noise when they’re distressed out of the water, which could perhaps be confused with a dog barking, while others say that it’s all nonsense and they don’t make any noises.

Although you can’t domesticate the mudpuppy, you can impress your friends with what you’ve learned in this article! Keep in mind that the humble mudpuppy is on the DNR’s endangered species/special watch list. If you’re visiting a lake and spot one lurking in the shallows, make sure to admire it from a distance.