I like the way you move

In which I talk about the “tailed”, belly flopping frog of North-West America.

I do like the way they move, but really it’s all about that landing.


Fun with frogs

I used to love playing with the frogs that hid along the side of my parent’s shed when I was a kid. Among a pile of rotting wood my brother and I would creep along, shifting the wood slowly to try and see what lay beneath. Then we’d jump back in surprise when a frog inevitably sprung out at us. That was all part of the fun though.

Once found, we would try and persuade the frog to jump again by tentatively touching the back end of the frog, causing us to jump back as it hopped up in response to the stimulation. I was recently surprised to find out that scientists use the same method that my brother and I once perfected to stimulate frog jumping. Only the scientists use it in experiments to analyze the distinctive frog movement, not as something to do on a lazy Saturday afternoon.

I discovered scientist’s investigation into frog hopping on a visit to the Burke museum (Seattle) in October. The museum has a range of exhibits, but it was a video in the “Discover Washington’s North Cascades” exhibit that caught my attention. It was the frog in this video, which I felt compelled to share about here.

The particular frog species, the Coastal tailed frog, turned out to be well worth me taking a closer look at, but for starters you should really take a look at them jumping:

A graceful frog

As you may have noticed, they BELLYFLOP! I’m hoping it’s not just me that found this hilarious. Although my laughter strikes as slightly hypocritical given that the video looks a lot like my attempt at a dive….

bellyflopBut why do they belly-flop when most sane frogs stay on their feet? Surely this is a less efficient and certainly less graceful manner of executing the frog’s signature spring?

The answer is yes, it is less efficient, or at least less useful, for the tailed frogs to land on their bellies. It delays them from executing a subsequent jump, making them easier prey to hunt down. Again, why???

The theory is that the tailed frog only needs the one jump to escape a predator and disappear into the watery depths of its habitat. Therefore, no cleaner landing technique was naturally selected in the species (i.e. landing well didn’t prove to be advantageous for the species and so didn’t emerge as a characteristic of this particular species).

And in-case you were worried about the frog’s belly burn post landing, don’t worry, the tailed frog has a fine sized pelvis and ribs in the abdomen to protect its internal organs from the belly-flop. So maybe the tailed frog isn’t in as much pain as I am when I “dive”.

The odd landing style of the tailed frog has led scientists’ to theorise that the ability to execute a more graceful landing is a later evolutionary quirk, perhaps of frogs that moved slightly further away from the confines of the pond.

That said, a pond is not an accurate description of the tailed frog’s habitat. This frog species thrives in fast, flowing turbulent streams- like those in the mountains of the Pacific North-West and they have developed a number of distinctive features in adapting to this environment. These adaptations were the cause of further amusement to me at the museum, which raises the question: how old is too old to be chuckling at animal genitalia in a museum?

The “tailed” frog

A modest frog

The person who first identified this frog species must have been pretty naïve to have named it the “tailed” frog. That ain’t no tail!

Although given the well documented science behind frog reproduction, perhaps it’s not so surprising that the naturalist did not assume the projection on the rear of the male tailed frogs was a penis.

In most frogs’ reproduction, eggs are produced by the female and then later fertilised by a spraying of male sperm. So usually there is no need for a protruding male sex organ for frog reproduction. However, with tailed frogs, the male have an appendage that allows for internal fertilisation of the eggs within the female.

These “tailed” guys are really quite different to other frogs. The male’s penis and the female’s ability to allow internal fertilisation of her eggs are thought to be adaptations to frog’s life in the fast flowing streams. I mean, imagine trying to fertilise eggs in the water against a current too strong for the soldiers to swim against? Nightmare.

Tadpole with sucker on display

And it’s not just the adult frogs that have had to make adjustments, no, the kids are just as effected by the turbulent home conditions. As tadpoles, the tailed frogs have to cling to the rocks in the stream to avoid being dragged downstream. The tadpoles have large sucker like mouths to enable them to cling to the rocks for dear life, and for the intake of nutritious algae.

However, these rough conditions do mean that tadpole development is pretty slow, taking anywhere from one to four years to complete their metamorphosis to adult froggy form. A tough life. But one that goes on for a bit- with coastal tailed frogs living for 15-20years! That is time for a lot of embarrassing belly-flop moments.


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