Photo of the Week – January 19, 2018

Let’s talk for a minute about the plains spadefoot and their awesome vertical-pupilled eyes.  You might think the spadefoot is a toad.  If so, you’re wrong  …kind of.  Also, you might think the word “pupilled” isn’t a real word, and anyway it should only have one ‘L’.  Wrong again – (I just looked it up).

The plains spadefoot (Spea bombifrons).  The coolest toad, or whatever it is, you’ll ever meet – if you’re ever lucky enough to meet one.

Toads, you see, have dry skin with little “warts” (no,they aren’t really warts, and don’t cause you to get warts).  Spadefoots have the kind of moist, slightly slimy skin that is more typical of frogs.  In addition, the plains spadefoot is missing the raised parotoid glands behind its eyes that are typical of true toads (see photo below).  So, clearly, the spadefoot is not a toad, it’s a frog.

True toads have dry warty skin and big parotoid glands behind their eyes, as seen in this boring, but useful, photo of a Great Plains toad (Anaxyrus cognatus).

Well, wait just a second, Herp-a-long Cassidy.  It’s not that simple.  As it happens, Anurans – the taxonomic group that includes frogs and toads – is a kind of spectrum, rather than two distinct types.  There are “true frogs” and “true toads”, but there are a lot of in-between species too, which don’t really fit either category.  Spadefoots don’t really identify as either frogs or toads.

The northern leopard frog (Rana pipiens) is one of the “true” frogs. If you watch them carefully, you might notice that they carry their noses just a little higher in the air than other so-called frogs.

Regardless of labels, the plains spadefoot is a fascinating creature, and one that is rarely seen, even in states like Nebraska where it is considered to be common.  In fact, despite the fact that it’s a grassland animal, and I’ve been exploring and studying grasslands for about 25 years, I’d never seen one in person until last summer.  (Thanks to Keith Geluso, by the way, for finding one at The Niobrara Valley Preserve and allowing me to photograph it!).

The reason they’re rarely seen is that plains spadefoots spend the vast majority of their lives underground, emerging only during and after heavy rains between April and July.  They are known as “explosive breeders” because they have to breed and get their offspring to maturity very quickly.  It’s a race between tadpoles and the temporary rain-filled ponds.  To help ensure survival, there are two types of spadefoot tadpoles; herbivores and carnivores/cannibals.  If the tadpole’s pond comes and goes so quickly that no algae or other vegetation has time to grow, at least some tadpoles can still find food – even if that food consists of siblings.  Spadefoots can go from egg to mature in around two weeks if they have to, which is pretty impressive.

Except for the brief periods when plains spadefoots make an appearance to breed and feed, they basically live their lives underground, in a kind of dormant state.  Their “‘spadefoot” moniker comes from a dark hard “spade” on their rear feet, which they use to quickly burrow down into loose soil.  While it might seem crazy that spadefoots live almost all of their lives in dormancy, there are a couple nice perks associated with the strategy.  First, it’s a pretty slick way to avoid predators.  Second, it allows spadefoots to colonize areas of grasslands far from permanent water – they don’t need access to streams, ponds, or lakes like their other Anuran cousins.  Instead, they just sit in quiet solitude until a good hard rain, and then party down.  All things considered, that might not be a terrible life.

Spadefoots are stinking cute.

Many thanks to Dan Fogell, both for his excellent book, “A Field Guide to Amphibians and Reptiles of Nebraska”, and for helping me better understand the frog-toad-etc spectrum this week.

This entry was posted in Prairie Animals and tagged , , , , , by Chris Helzer. Bookmark the permalink.

About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.

15 thoughts on “Photo of the Week – January 19, 2018

  1. Cool blog, Chris. Spadefoots are to me like otters to you.
    (There, I may have settled Nikki’s question, too. :-) )
    By the way, you state that “there are a lot of in-between species too, which don’t really fit either category”. It might be better to say that the other species are on the side, and even on altogether different branches of the froggish-animal family tree, e.g.,

    • Thanks James. They really are elusive, aren’t they?? I think your point about where the other species fall on the “spectrum” is a good one. I actually spent a fair amount of time looking for a visual like the one you linked to, and couldn’t find one. I was having trouble visualizing the relationships between the groups. That image is very helpful.

  2. I’ve found leopard frogs high up on hillsides in the Loess Hills quite far from water sometimes. I’ve wondered how they keep moist in such a dry environment, since it would seem they would have a real risk of desiccation.

  3. This was fascinating. When I read about their practice of going underground and waiting for rain, I started wondering about Hueco Tanks in west Texas. The rocks there form shallow pools of various sizes which only hold water during seasonal rains. Sure enough, there are three species of spadefoot there. I’ve not explored it any further yet, but I’m looking forward to it. Great article.

  4. I’ve often wondered if animals that spend a great amount of time in dormancy are in touch with the Universe in a way that we, who spend our time on the go, are not. Are they in a state of meditation? Are they working in concert with others in the Universe to keep things running? If so, we are more imperiled than we think when we allow such animals to go extinct.



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