uroplatus geckos

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Uroplatus phantasticus by Mark Scherz

Mossy Frogs: Convergent Crypsis

Alright, sit down, shut up, and let me tell you about some of the coolest frogs in the whole damn world. Someone sent an ask about my favourite example of convergence; this is way up there.

You may have heard of the Vietnamese Mossy Frog, Theloderma corticale, pictured top right in the figure above. This awesome little bastard is now quite common in the pet trade because of how bitching its camouflage makes it look. This is a really fucking awesome example of crypsis, because when these frogs are at rest among moss, they are almost imperceptible.

What makes it so hard to see? Well, for one, it’s fucking green. That’s pretty effective as camouflage when you live on moss. That green isn’t solid though, like a lame-ass Hyla arborea. No, it’s mottled with brown and other shades of green, to break up any solid colours. Next, it has spines all over and around its body, especially on the edges of its limbs. What do these do? They break up the outline of the frog. It doesn’t cast a frog-shaped shadow. This makes it much harder to spot, and is just generally awesome.

But this is Fuck Yeah, Convergent Evolution, not Fuck Yeah, Crypsis! (Yeah that’s a thing now too, I couldn’t help myself).

The green colour and spiny body, often with fringes around the limbs and body, has evolved in many many animals (including my favourites, the Uroplatus geckos).

The evolutionary pressure for this kind of crypsis is so great that incredibly similar structures and body shapes have evolved at least. seven. fucking. times. in at least four families of frogs! There may even be more but I don’t know all of the world’s frog species. These are just the ones I knew of already and a few added by Prof. Karen Lips and Dr. Jodi Rowley (two of the coolest herpetologists on the internet).

In Madagascar alone we have three convergences on this mossy crypsis: some frogs in the genus Spinomantis (Mantellidae:Mantellinae), including S. spinosa depicted above, and the aptly named S. phantasticus; a few frogs in the genus Scaphiophryne (Microhylidae:Scaphiophryninae); and Platypelis grandis (Microhylidae:Cophylinae). These three groups have few things in common, but chief among them is a predilection for moist mossy habitats.

The common ancestor of all seven of these radiations hopped the earth hundreds of millions of years ago. It was barely even a frog, let alone a fucking awesome moss mimic.

The similarity we see in these frogs can therefore mean only one thing: the evolutionary pressures they are experiencing (e.g. being eaten) are selecting for the same solution: bad-ass crypsis. And rather than re-inventing the wheel of crypsis, each group has found the same solution: textured skin to break up the shadow and outline of the body, and mottled green colouration to blend into the foliage.

The convergence is so extreme that you would be forgiven for thinking most of these species to belong to the same genus if you didn’t know they were from completely different sides of the earth.

Convergent evolution is the fucking best.

This is Breaking, or Break for short, she is a female U. Phantasticus.

Breaking is an unusual animal because her tail is all red with that charcoal tip.  Why is that unusual?  Well, it wasn’t that color when I bought her, but it has changed over time.  This is also her original tail, she has never dropped it (as Phants cannot regenerate tails anyway).  Her tail continues to change color gradually.

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Uroplatus sikorae

Photo by Rich