These miniature frogs have lost the ability to jump

Setting a record at being the first ones known to do so

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These miniature frogs have lost the ability to jump

The Earth is full of tiny amphibians. For example, Paedophryne amauensis is a species of microhylid frog endemic to eastern Papua New Guinea. At 7.7 mm (0.30 in) in snout-to-vent length, it is considered the world’s smallest known vertebrate. According to a new study published in the journal Scientific Advances, being that tiny comes with a price. In this study, researchers showed that pumpkin toadlets and flea toads in the genus Brachycephalus have become so small that they have lost the ability to maintain their balance when jumping.

How has it happened?

Four different species of in the genus Brachycephalus, whose home is Brazil’s tropical Atlantic Forest, were studied. The minature frogs did jump when gently prodded but then lose control in mid-air and crash. This was due to all of them having small vestibular systems (a network of spiral chambers fill with fluid inside the inner earts of animals), with the pumpkin toadlets having the smallest one measured in any vertebrate to date. When an animal moves its head the liquid inside the vestibular chambers also moves and touches tiny hairs inside its ears. This sends electrical signals to the brain that help the organism maintain its balance (among other things such as detecting acceleration and knowing up from down). For tiny vetebrates, the vestibular system takes up proportionally more space inside the skull and the canals are as big as they can be but they are still not big enough for the liquid to move at a rate that would allow for them to maintain their balance.

Microcomputed tomography (microCT) imaging of the inner ear of Ischnocnema guentheri, B. brunneus, B. pernix, B. coloratus, and B. sulfuratus.

Microcomputed tomography (microCT) imaging of the inner ear of Ischnocnema guentheri, B. brunneus, B. pernix, B. coloratus, and B. sulfuratus.

 

“The semicircular canals of miniaturized frogs are the smallest recorded for adult vertebrates, resulting in low sensitivity to angular acceleration due to insufficient displacement of endolymph. This translates into a lack of postural control during jumping in Brachycephalus and represents a physical constraint resulting from Poiseuille’s law, which governs movement of fluids within tubes”, say the authors in the study.

Over the years miniature frogs in this family have been studied a lot. It seems they have developed various unique characteristics to survive. Below are the photos of some of them.

 

This species of pumpkin toadlet, Brachycephalus albolineatus was described by scientists in 2016. PHOTO BY BORNSCHEIN ET AL. (2016), CC-BY-NC

Species of pumpkin toadlet, Brachycephalus albolineatus described in 2016. PHOTO BY BORNSCHEIN ET AL. (2016), CC-BY-NC

 

Scientists are discovering new species of Brachycephalus on a regular basis, such as this B. auroguttatus described in 2015. PHOTO BY RIBEIRO ET AL. (2015) CC-BY-NC

This B. auroguttatus was first described in 2015. PHOTO BY RIBEIRO ET AL. (2015) CC-BY-NC)

 

Some Brachycephalus frogs, such as this B. coloratus described in 2017, have bright coloration that warns predators of their toxicity. PHOTO BY RIBEIRO ET AL. (2017) CC-BY-NC

Members of this species: B. coloratus, described in 2017, have bright coloration that warns predators of their toxicity. PHOTO BY RIBEIRO ET AL. (2017) CC-BY-NC

 

Flea toads, such as this Brachycephalus curupira are a bit drab compared to their pumpkin toadlet relatives, a condition that helps them blend in with the brown tones of forest floors. PHOTO BY RIBEIRO ET AL. (2017) CC-BY-NC

Flea toads, such as this Brachycephalus curupira are not so bright as the pumpkin toadlet, which helps them blend in with the brown tones of forest floors. PHOTO BY RIBEIRO ET AL. (2017) CC-BY-NC

 

Aside from their inability to jump, their small size has also placed restrictions on the anatomy of Brachycephalus frogs, demonstrated by this B. verrucosas which has fewer toes than most other frogs. PHOTO BY RIBEIRO ET AL. (2015), CC-BY-NC

Brachycephalus frogs can’t jump and some have other restrictions such as this B. verrucosas which has fewer toes than most other frogs. PHOTO BY RIBEIRO ET AL. (2015), CC-BY-NC

 

Aren’t they absolutely adorable and isn’t evolution absolutely fantastic?

Full study and source: SCIENCE ADVANCES 15 Jun 2022 Vol 8Issue 24 DOI: 10.1126/sciadv.abn1104

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I am a Chartered Environmentalist from the Royal Society for the Environment, UK and co-owner of DoLocal Digital Marketing Agency Ltd, with a Master of Environmental Management from Yale University, an MBA in Finance, and a Bachelor of Science in Physics and Mathematics. I am passionate about science, history and environment and love to create content on these topics.