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What the sources say

Glass FrogCentrolenidae

Every figure, record and mechanism on the Glass Frog profile was written from a source, and this is the working table behind it: 49 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Barnett et al. 2020

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

The page saysSee-through belly skin that shows off a beating heart
The source saystransparent ventral skin through which their bones, intestines, and beating hearts can be seen
The page saysGlass frogs are well known for their see-through ventral (belly) skin, through which "bones, intestines, and beating hearts can be seen,"
The source saysGlass 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
The page saysTheir backs carry sparse pigment, so glass frogs are better described as translucent
The source sayssparse dorsal pigmentation means that these frogs are better described as translucentNote: 'so' is the source's own link: 'sparse dorsal pigmentation means that'; dorsal = back
The page saysA 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 source saysthe perceived luminance of the frogs changed depending on the immediate background, lowering detectability and increasing survival when compared to opaque frogsNote: 2020 is the reference's publication year
The page saysThe 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
The source saysthis 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 page saysThe researchers suggest this is a camouflage strategy and named it "edge diffusion."
The source sayssuggests a camouflage strategy, "edge diffusion,"
The page saysGlass frogs (family Centrolenidae) are well known for their see-through ventral (belly) skin, through which their bones, intestines and beating hearts can be seen
The source saysare well known for their transparent ventral skin through which their bones, intestines, and beating hearts can be seen
The page saysTheir backs carry sparse pigment, though, so they are better described as translucent
The source sayssparse dorsal pigmentation means that these frogs are better described as translucentNote: 'so' is the source's own link: 'sparse dorsal pigmentation means that'; dorsal = back
The page saysA 2020 study found that their perceived brightness shifts with the background behind them
The source saysthe perceived luminance of the frogs changed depending on the immediate backgroundNote: 2020 is the reference's publication year
The page saysthe 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
The source saysthis 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 page saysThe researchers suggest this is a camouflage strategy and named it "edge diffusion."
The source sayssuggests a camouflage strategy, "edge diffusion,"

Source
02

Taboada et al. 2022

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

The page saysa liver that can hide most of the frog's red blood cells
The source saysremoving ~89% of their RBCs from circulation and packing them within their liverNote: most = the study's ~89%
The page saysResting glass frogs in a 2022 study packed about 89% of their red blood cells into their livers, becoming two to three times more transparent
The source saysresting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liverNote: 2022 is the reference's publication year
The page saysRed blood cells strongly dim the light passing through them, which makes transparency hard for animals with backbones
The source saysIn vertebrates, attaining transparency is difficult because their circulatory system is full of red blood cells (RBCs) that strongly attenuate lightNote: attenuate light = dim it; vertebrates = animals with backbones
The page saysA 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
The source saysresting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liverNote: 2022 is the reference's publication year
The page sayswithout the blood clotting
The source saysregulate the location, density, and packing of RBCs without clotting
The page saysIn its liver
The source sayspacking them within their liver
The page saysRed blood cells strongly dim the light passing through them, which makes transparency hard for animals with backbones
The source saysIn vertebrates, attaining transparency is difficult because their circulatory system is full of red blood cells (RBCs) that strongly attenuate light
The page saysA 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
The source saysresting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liverNote: 2022 is the reference's publication year
The page saysThey did this without the blood clotting, which the authors say offers insight for research on metabolism, blood flow and blood clots
The source saysglassfrogs' ability to regulate the location, density, and packing of RBCs without clotting offers insight in metabolic, hemodynamic, and blood-clot researchNote: hemodynamic = blood flow
The page saysa frog that packs its red blood cells into its liver to stay transparent
The source saysresting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liver

Source
03

AmphibiaWeb, University of California, Berkeley

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

The page saysgreen bones
The source saysMembers of this family also have green bones
The page saysHumid forests with streams, in mountains and lowlands, from Central America south through Venezuela, Bolivia, Argentina and southern Brazil
The source saysSpecies of this group occur from Central America south through Venezuela, Bolivia, Argentina, and southern Brazil in high montane forests with streams.
The page saysin many species the internal organs show
The source saysthe transparent ventral skin, through which internal organs can be seen in many species
The page saysCentrolene geckoideum reaches 77 mm, about three inches
The source saysCentrolene geckoideum , which attains a length of 77 mmNote: 77 mm = 3.03 in
The page saysAmphibiaWeb lists 171 species in 12 genera
The source saysCentrolenidae 171 species in 12 genera
The page saysliving in humid forests with streams from Central America south through Venezuela, Bolivia, Argentina and southern Brazil
The source saysSpecies of this group occur from Central America south through Venezuela, Bolivia, Argentina, and southern Brazil in high montane forests with streams.
The page saysin mountains and lowlands alike
The source saysInhabits wet montane rainforests
The page saysGlass frogs have green bones as a result of green bile salts, and green bones are one of the traits that unite the family
The source saysMembers of this family also have green bones as a result of green bile salts. ... Morphological characters uniting this clade are: ... 9) green bones
The page saysGlass frog skin also holds a pigment that reflects infrared light at the same wavelengths plants do, possibly another way to stay hidden
The source saysStudies 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.
The page saysGlass frogs usually lay their eggs on rocks or plants overhanging water
The source saysEggs are usually deposited on rocks or plants overhanging water
The page saysobserved parental care in every one, including eight species where care had never been documented
The source saysParental care was observed for all 40 species, including eight for which care has never been documented.
The page saysGlass frogs (Centrolenidae) have green bones as a result of green bile salts, and green bones are one of the traits that unite the family
The source saysMembers of this family also have green bones as a result of green bile salts. ... Morphological characters uniting this clade are: ... 9) green bones
The page saysYes. 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
The source saysOctober 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 page saysThe 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 source saysThe 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.

Source
04

Animal Diversity Web, University of Michigan

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

The page saysHumid forests
The source saysDistribution is limited to the humid neotropics
The page saysMost species are smaller than 30 mm long, about an inch
The source saysMost species are smaller than 30 mm total body lengthNote: 30 mm = 1.18 in, rounded to about an inch
The page saysThe greatest diversity is on the slopes of the Andes and in Costa Rica and Panama
The source saysDistribution is limited to the humid neotropics, with the greatest diversity on the slopes of the Andes, as well as in Costa Rica and Panama.

Source
05

Delia, Bravo-Valencia & Warkentin 2017

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

The page saysThe 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
The source saysOur 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

Source
06

The Brink, Boston University

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

The page saysUntil recently, biologists thought the eggs of most species got no help from either parent
The source saysUntil recently, biologists thought the eggs of most species were on their own during this vulnerable stage, without any help from mom or dad.
The page saysa field study of 40 species, run over six rainy seasons
The source saysobserve nighttime parental behavior among no fewer than 40 species of glassfrogs ... Delia and Bravo Valencia pursued their project over six rainy seasons
The page saysIn 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
The source saysspotted 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
The page saysIn experiments on two species in Panama, mothers soaked up water from damp spots on leaves and delivered it to their eggs
The source saysperformed 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 page saysThe 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 source saysThe 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

Source
07

Delia, Ramírez-Bautista & Summers 2014

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

The page saysin Hyalinobatrachium fleischmanni, embryos hatched early when their father was removed, but stayed longer in the egg when he kept caring
The source saysembryos 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.

Source
08

Schwalm, Starrett & McDiarmid 1977

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

The page saysA 1977 study that included two glass frog species suggested this could also help them control body temperature
The source saysTwo 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

Source
09

Cisneros-Heredia et al. 2009

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

The page saysin mountains and lowlands
The source saysmany lowland glassfrogs are conspicuous members of riverine communitiesNote: scope only: the family includes lowland species; 'many' qualifies how conspicuous they are, and the page claims no number
The page saysin mountains and lowlands alike
The source saysmany lowland glassfrogs are conspicuous members of riverine communitiesNote: scope only: the family includes lowland species; 'many' qualifies how conspicuous they are, and the page claims no number
The page saysIn 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
The source saysWe 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

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.