Posted by: Rob Viens | May 4, 2012

A Chorus of Frogs

On May 4th Darwin was still recovering from his adventures on the Warspite yesterday.  His imagination was still running wild:

“Worked away at my usual employments, & filled up the cracks in the time by building castles in the air about the “pomp & circumstance of war”. ” (May 4)

I am particularly fond of the idea of “filling the cracks” of the day – I might have to “steal” that phrase. But what to write about today…?

In his Zoological Journal (around this time) Darwin writes about a “Hyla” he collected.  I like the many different shades of yellow he describes:

“On the back, a band of “yellowish brown” width of head, sides copper yellow; abdomen silvery yellowish white slightly tuberculated: beneath the mouth, smooth dark yellow.— under sides of legs leaden flesh colour.— Can adhere to perpendicular surface of glass.” (Zoological Journal)

Hyla are a genus of tree frogs consisting of 33 different species found all over the world (though many more species were formally placed in the Hyla genus).  It appears that several of them are found in Brazil, so it is unclear what species Darwin observed (and the sample he collected seems to have been lost, so it never made it into the Zoology books published after the voyage).

So – in the interest of seeing a similar species – here are a couple of Hyla species that more or less  fit the Darwin’s description – the Hispaniolan yellow tree frog (from Arkive.org) and the Golden Lesser tree frog (from http://www.futurity.org/).  The later is from the Brazilian Atlantic forest and appears (at least from the bottom) that it could be Darwin’s Hyla. Notice the slightly bumpy (tuberculated) and silvery underbelly.

Hispaniolan yellow tree frogGolden lesser tree frog

Tree frogs have sticky pads on their feet that behave sort of like suction cups – allowing them to stick to most smooth surfaces (such as glass). One recent study (Tree Frogs’ Self-Cleaning Feet Could Solve a Sticky Problem) notes that in order to be effective, tree frog feet must be self-cleaning (think about what happens to tape when it gets dirty).  More interestingly, they go on to suggest that we could use this “technology” to create cleaner bandages and other self-cleaning sticky surfaces.  Biomimicry rocks!

Being a true naturalist, Darwin uses all of his senses and goes on to describe the sound of the tree frogs:

“The fields resound with the noise which this little animal, as it sits on a blade of grass about an inch from the water, emits.— The note is very musical. I at first thought it must be a bird.— When several are together they chirp in harmony; each, beginning a lower note than the other, & then continuing upon two (I think these notes are thirds to each other).” (Zoological Journal)

Green Tree Frog chirps (from YouTube):

Frog sounds are so varied from species to species (all the better to finds a mate), so be sure to check out these additional links to frog sounds – All About Frogs and Listen to Nature – Frogs and Toads

By the way – the name Hyla is derived from Hylas –  the companion of Heracles and one of the Argonauts in Greek mythology. He was  abducted by water nymphs and never seen again (poor guy). I suspect that the species was named because of Hylas’ connection to water, but am not sure.

Hylas and the Nymphs by John William Waterhouse (1896)

Hylas and the Nymphs

OK – time to let some of those frog recordings serenade me to sleep. (RJV)

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Responses

  1. […] For some frog sounds, be sure to look back a couple of weeks ago to the post – A Chorus of Frogs. […]


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