---
title: "What the sources say about the Glass Frog | AnimalTracks.wiki"
description: "49 claims from the Glass Frog profile, each beside the words of the source that backs it."
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canonical: "https://animaltracks.wiki/animals/glass-frog/sources/"
---

# What the sources say about the Glass Frog (*Centrolenidae*)

> 49 claims from the Glass Frog profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Glass Frog](https://animaltracks.wiki/animals/glass-frog/)

## Barnett et al. (2020). Imperfect transparency and camouflage in glass frogs. Proceedings of the National Academy of Sciences.

https://doi.org/10.1073/pnas.1919417117

| The page says | The source says |
| :--- | :--- |
| See-through belly skin that shows off a beating heart | transparent ventral skin through which their bones, intestines, and beating hearts can be seen |
| Glass frogs are well known for their see-through ventral (belly) skin, through which "bones, intestines, and beating hearts can be seen," | Glass frogs are one example of terrestrial transparency and are well known for their transparent ventral skin through which their bones, intestines, and beating hearts can be seen |
| Their backs carry sparse pigment, so glass frogs are better described as translucent | sparse dorsal pigmentation means that these frogs are better described as translucent (note: 'so' is the source's own link: 'sparse dorsal pigmentation means that'; dorsal = back) |
| A 2020 study found that their perceived brightness shifts with the background behind them, making them harder to detect and more likely to survive than opaque frogs | the perceived luminance of the frogs changed depending on the immediate background, lowering detectability and increasing survival when compared to opaque frogs (note: 2020 is the reference's publication year) |
| The shift was greatest in the legs, which surround the body at rest and blur the line between background and frog instead of leaving a sharp, eye-catching edge | this change was greatest for the legs, which surround the body at rest and create a diffuse transition from background to frog luminance rather than a sharp, highly salient edge |
| The researchers suggest this is a camouflage strategy and named it "edge diffusion." | suggests a camouflage strategy, "edge diffusion," |
| Glass frogs (family Centrolenidae) are well known for their see-through ventral (belly) skin, through which their bones, intestines and beating hearts can be seen | are well known for their transparent ventral skin through which their bones, intestines, and beating hearts can be seen |
| Their backs carry sparse pigment, though, so they are better described as translucent | sparse dorsal pigmentation means that these frogs are better described as translucent (note: 'so' is the source's own link: 'sparse dorsal pigmentation means that'; dorsal = back) |
| A 2020 study found that their perceived brightness shifts with the background behind them | the perceived luminance of the frogs changed depending on the immediate background (note: 2020 is the reference's publication year) |
| the shift is greatest in the legs, which surround the body at rest and blur the line between background and frog instead of leaving a sharp edge | this change was greatest for the legs, which surround the body at rest and create a diffuse transition from background to frog luminance rather than a sharp, highly salient edge |
| The researchers suggest this is a camouflage strategy and named it "edge diffusion." | suggests a camouflage strategy, "edge diffusion," |

## Taboada et al. (2022). Glassfrogs conceal blood in their liver to maintain transparency. Science.

https://doi.org/10.1126/science.abl6620

| The page says | The source says |
| :--- | :--- |
| a liver that can hide most of the frog's red blood cells | removing ~89% of their RBCs from circulation and packing them within their liver (note: most = the study's ~89%) |
| Resting glass frogs in a 2022 study packed about 89% of their red blood cells into their livers, becoming two to three times more transparent | resting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liver (note: 2022 is the reference's publication year) |
| Red blood cells strongly dim the light passing through them, which makes transparency hard for animals with backbones | In vertebrates, attaining transparency is difficult because their circulatory system is full of red blood cells (RBCs) that strongly attenuate light (note: attenuate light = dim it; vertebrates = animals with backbones) |
| A 2022 study found that while resting, glass frogs pulled about 89 percent of their red blood cells out of circulation and packed them into their livers, becoming two to three times more transparent | resting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liver (note: 2022 is the reference's publication year) |
| without the blood clotting | regulate the location, density, and packing of RBCs without clotting |
| In its liver | packing them within their liver |
| Red blood cells strongly dim the light passing through them, which makes transparency hard for animals with backbones | In vertebrates, attaining transparency is difficult because their circulatory system is full of red blood cells (RBCs) that strongly attenuate light |
| A 2022 study found that resting glass frogs pulled about 89 percent of their red blood cells out of circulation and packed them into their livers, becoming two to three times more transparent | resting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liver (note: 2022 is the reference's publication year) |
| They did this without the blood clotting, which the authors say offers insight for research on metabolism, blood flow and blood clots | glassfrogs' ability to regulate the location, density, and packing of RBCs without clotting offers insight in metabolic, hemodynamic, and blood-clot research (note: hemodynamic = blood flow) |
| a frog that packs its red blood cells into its liver to stay transparent | resting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liver |

## Centrolenidae (Glass Frogs). AmphibiaWeb, University of California, Berkeley.

https://amphibiaweb.org/lists/Centrolenidae.shtml

| The page says | The source says |
| :--- | :--- |
| green bones | Members of this family also have green bones |
| Humid forests with streams, in mountains and lowlands, from Central America south through Venezuela, Bolivia, Argentina and southern Brazil | Species of this group occur from Central America south through Venezuela, Bolivia, Argentina, and southern Brazil in high montane forests with streams. |
| in many species the internal organs show | the transparent ventral skin, through which internal organs can be seen in many species |
| Centrolene geckoideum reaches 77 mm, about three inches | Centrolene geckoideum , which attains a length of 77 mm (note: 77 mm = 3.03 in) |
| AmphibiaWeb lists 171 species in 12 genera | Centrolenidae 171 species in 12 genera |
| living in humid forests with streams from Central America south through Venezuela, Bolivia, Argentina and southern Brazil | Species of this group occur from Central America south through Venezuela, Bolivia, Argentina, and southern Brazil in high montane forests with streams. |
| in mountains and lowlands alike | Inhabits wet montane rainforests |
| Glass frogs have green bones as a result of green bile salts, and green bones are one of the traits that unite the family | Members of this family also have green bones as a result of green bile salts. ... Morphological characters uniting this clade are: ... 9) green bones |
| Glass frog skin also holds a pigment that reflects infrared light at the same wavelengths plants do, possibly another way to stay hidden | Studies have shown that glass frogs contain a unique pigment in their skin that reflects the same wavelength infrared radiation that plants do, possibly another adaptation for concealment. |
| Glass frogs usually lay their eggs on rocks or plants overhanging water | Eggs are usually deposited on rocks or plants overhanging water |
| observed parental care in every one, including eight species where care had never been documented | Parental care was observed for all 40 species, including eight for which care has never been documented. |
| Glass frogs (Centrolenidae) have green bones as a result of green bile salts, and green bones are one of the traits that unite the family | Members of this family also have green bones as a result of green bile salts. ... Morphological characters uniting this clade are: ... 9) green bones |
| Yes. A study of 40 glass frog species, highlighted by AmphibiaWeb in October 2017, observed parental care in all 40, including eight for which care had never been documented | October 23, 2017: Parental care in frogs is a fascinating, yet understudied facet of amphibian behavioral ecology. ... Their integrative study of 40 species ... Parental care was observed for all 40 species, including eight for which care has never been documented. |
| The caregiving sex varied across the family, and the study's analysis suggested that care by males evolved two to three times from care by females alone | The care-giving sex was variable across the family, and phylogenetic analyses suggested that rather than no care-to-male care transitions, male care evolved two to three times from female-only care. |

## Centrolenidae (Glass Frogs, Leaf Frogs). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Centrolenidae/

| The page says | The source says |
| :--- | :--- |
| Humid forests | Distribution is limited to the humid neotropics |
| Most species are smaller than 30 mm long, about an inch | Most species are smaller than 30 mm total body length (note: 30 mm = 1.18 in, rounded to about an inch) |
| The greatest diversity is on the slopes of the Andes and in Costa Rica and Panama | Distribution is limited to the humid neotropics, with the greatest diversity on the slopes of the Andes, as well as in Costa Rica and Panama. |

## Delia, Bravo-Valencia & Warkentin (2017). Patterns of parental care in Neotropical glassfrogs: fieldwork alters hypotheses of sex-role evolution. Journal of Evolutionary Biology.

https://doi.org/10.1111/jeb.13059

| The page says | The source says |
| :--- | :--- |
| The study's analysis suggests care by fathers alone evolved two or three times from care by mothers alone, a switch linked to much higher levels of care | Our analyses support that male-only care evolved 2-3 times from female-only care, and this change is associated with substantial increases in care levels |

## (Some) Frogs Are Better Parents Than We Thought. The Brink, Boston University.

https://www.bu.edu/articles/2017/some-frogs-are-better-parents-than-we-thought/

| The page says | The source says |
| :--- | :--- |
| Until recently, biologists thought the eggs of most species got no help from either parent | Until recently, biologists thought the eggs of most species were on their own during this vulnerable stage, without any help from mom or dad. |
| a field study of 40 species, run over six rainy seasons | observe nighttime parental behavior among no fewer than 40 species of glassfrogs ... Delia and Bravo Valencia pursued their project over six rainy seasons |
| In many species, mothers brood, or sit on, their eggs through the night the eggs are fertilized, which improves their survival, while in almost a third of species, fathers stand guard for much longer | spotted a glassfrog mother sitting on her clutch of eggs. ... in many species, glassfrog mothers brood their eggs during the night the eggs are fertilized, and that this care improves the survival of the eggs, while in almost a third of species, glassfrog fathers stay on guard for much longer periods |
| In experiments on two species in Panama, mothers soaked up water from damp spots on leaves and delivered it to their eggs | performed experiments on two species of frogs in Panama. ... the eggs given maternal care survived significantly better than those that did not receive care. The key to this survival was that the frogs were soaking up water from damp spots on leaves and delivering it to the eggs. |
| The jelly around the eggs swelled to about four times its thickness, so an egg-eating katydid, a cricket-like insect, that bit in got mouthfuls of jelly and generally gave up | The jelly surrounding the eggs then would swell up with water and grow about four times thicker. Offering these swollen egg packages to katydids, crickets that prey on frog eggs ... so when the katydid bites, it's getting mouthfuls of jelly, and it generally gives up |

## Delia, Ramírez-Bautista & Summers (2014). Glassfrog embryos hatch early after parental desertion. Proceedings of the Royal Society B: Biological Sciences.

https://doi.org/10.1098/rspb.2013.3237

| The page says | The source says |
| :--- | :--- |
| in Hyalinobatrachium fleischmanni, embryos hatched early when their father was removed, but stayed longer in the egg when he kept caring | embryos hatch early to cope with paternal abandonment in the glassfrog Hyalinobatrachium fleischmanni (Centrolenidae). We conducted male-removal experiments in a wild population ... Embryos hatched early when abandoned, but extended development in the egg stage when fathers continued care. |

## Schwalm, Starrett & McDiarmid (1977). Infrared Reflectance in Leaf-Sitting Neotropical Frogs. Science.

https://doi.org/10.1126/science.860137

| The page says | The source says |
| :--- | :--- |
| A 1977 study that included two glass frog species suggested this could also help them control body temperature | Two members of the glass-frog family Centrolenidae (Centrolenella fleischmanni, C. prosoblepon) ... reflect near-infrared light (700 to 900 nanometers) ... Infrared reflectance may confer adaptive advantage to these arboreal frogs both in thermoregulation and infrared cryptic coloration. (note: 1977 is the reference's publication year) |

## Cisneros-Heredia et al. (2009). Endemic Ecuadorian glassfrog Cochranella mache is Critically Endangered because of habitat loss. Oryx.

https://doi.org/10.1017/s0030605309990640

| The page says | The source says |
| :--- | :--- |
| in mountains and lowlands | many lowland glassfrogs are conspicuous members of riverine communities (note: scope only: the family includes lowland species; 'many' qualifies how conspicuous they are, and the page claims no number) |
| in mountains and lowlands alike | many lowland glassfrogs are conspicuous members of riverine communities (note: scope only: the family includes lowland species; 'many' qualifies how conspicuous they are, and the page claims no number) |
| In 2009, a study of one Ecuadorian species, Cochranella mache, recommended listing it as Critically Endangered because of the continuing destruction of its increasingly fragmented habitat | We recommend that the species should be categorized as Critically Endangered because of the continuous and progressive destruction of its increasingly fragmented habitat. (note: 2009 is endemic-2009's publication year (reference metadata); Ecuadorian is in the title, Endemic Ecuadorian glassfrog Cochranella mache) |