Species Endangered (MS-Blog Series from) XII / 09

Gastric-brooding Frog

Class: Amphibia

Order: Anura

Latin name: Rheobatrachus silus / R. Vitellinus

Range: (Australia) - Inhabited a limited ranges at eastern Queensland.

IUCN: EX (CR) / EX (CR)¹, CITES: -/- (not checked)

(a 2009 situation)

Sometimes word of the day, frogs are more important than people usually realize. Them are – like echoed also by us in our earlier amphibian post – supposed most threatened from the animal orders, not the least by the climatic change, etc. But, as they also are often mentioned having been first species that moved from seas to the land, one easily presumes them most 'primitive' of the terrestrial animals. In fact that appears false assumption, for we learn that their extant main groups (Frogs, Salamanders, and limbless Caecilians) actually are timed roughly for the same periods as the modern reptiles. Oldest from reptiles still extant genera, turtles and crocodiles therefore appear slightly more distant from evolutionary origins than current amphibians families, it seems. (However, also appears stated that earliest amphibians were around some 300+ Million years in the past, already). In spite of how exciting these preceding view-points might be, our interest in this (brief) text is delimited for the variety of colourful amphibian species. Since the rain forest species are not only most numerous but most impressive from looks (as well most threatened of them, also often said), this consists largely from representing them.

So, the above frog(s) examples for this part, are not selecte from the reason of being extinct – actually they represent only singular species among several mentioned in this text. Nevertheless, and like we find mentioned, the Rheobatrachus (genus of frogs) contained above mentioned two species (R. Silus/.Vitellinus), both rather exceptional. Mentioned as gastric-brooding frogs from the reason that in both the reproduction was by female frog ingesting it's (fertilized) eggs, which then developed for juveniles in the frogs stomach (and were finally vomited as juveniles from it's mouth). Unique manner even among the frogs which show multitudes of variety and peculiar examples at their reproduction. In our only marginal acquaintance from the life of the frogs, this makes us almost to think the truth often being stranger than fiction.

Anyway, sad part of course is that no Gastric-brooding frog seems been found after their rapid disappearance during brief period in begins of 1980s (Been only known for science since about 1972/3). At that time the reasons and causes for frog extinctions in general weren't yet too clearly understood, and so, in lack of any especial knowledge from the species we're not focusing on that here more precisely. However, at the amphibian declines generally, an increased vulnerability of the small frog populations is nowadays often mentioned. Most alarming prospect, equally often noticed, is their habitat fragmentation(/destruction), like mentioned in following paragraphs:

"Shrinking Habitats. Pressure generated by the world's expanding human population creates an insatiable demand for land that results in the destruction of the natural habitat of plants and animals. This process is offset, to a very small degree, by the creation of natural reserves, but these can become prisons rather than havens for animals such as amphibians. Many amphibians live in small, local populations, the longterm survival of which depends on the occasional immigration of animals from other such populations elsewhere. Increasingly, amphibians are being forced to live in fragmented landscapes within roads, built-up land, and agriculture separating one population from another. There is growing evidence that this isolation leads to an inbreeding and a consequent loss of genetic diversity, decreased survival rates and an increased incidence of anatomical deformities.”(Halliday-Adler 2002, p. 32-33)

As well is said: “Although amphibian population declines have attracted a great deal of scientific and media interest, there is no reason to think they are unusual or unique. All the factors that adversely impact upon amphibians pose a threat to other forms of wildlife. [...]"(Halliday-Adler 2002, ibid.) ...Remarks at the book then continue with mentioning the disappearance in freshwater habitats noticeably having impaired the amphibians populations for some time (other wildlife as well). Also, fx how the protected areas should be designed to create optimal conditions in nature reserves is stated being increasingly important, since the populations based on single limited area are more likely to face eventual extinction, sometimes despite protection. As well appears noticed, that for smaller part/some level the diminished habitat can be replaced by habitat creation - like the underpasses and tunnels built in some places to create amphibians some safety from roadkills, fx on routes for their breeding sites (ao efforts at their protection mentioned). (Halliday-Adler, p. 33-35) Remembering that (in cases) populations of thousands individual frogs have been noticed rapidly vanished (as result of increased vulnerability to variety of threat), also gives some importance for the above mentioned.

The amphibian decline in overall presented at our earlier post, we'll leave that for these few words and the following text mostly serves the purpose of presenting examples from variety in the amphibian lifes. But, fx the Amphibia web's pages about the global decline contain some further information, probably (also seems contain the downloadable Amphibian Action Conservation Plan). And for the interested, from various threatened amphibian around world, EDGE's Amphibian top 100 list presents many, any of those less usually or not commonly noticed. (And – further more - not forgetting to mention this word on behalf the amphibians ; we also learns from it about another exciting frog species, the Phantasmal poison frog (EN), whose skin secretions contain some particular compounds, possibly found of use in the human medicinery as well as aid in the research of pain-killer medicines (or something like that, sounds not at all too unsual or surprising, concerning the amphibians have especial skin formations in overall, etc) - Even though I find that least interesting from aspects presented on the text (Maybe so 'cause I don't much care from the medicines markets and labs, and even less from the prospective views of the global medical businesses or firms. Nevertheless, despite my slight antipation, it's sometimes mentioned that penicillin probably has been one of the most benefiting inventions in the preceding century - for human kind.)

...But for to stay on our main topic in this; following paragraphs are focused on colourful and exciting characteristics of the amphibians. Many of the species mentioned in the following, I suppose, are from the better known colourful and sometimes also the most usually represented examples. In spite of that, there's a lot especial and interesting in them to familialirize with (So I noticed when writing this...).

Often in the nature, bright colour serves purposes of aposematism (ie as warning sign to potential predators from species being distasteful/of it's toxic defenses). Some frogs also exhibit polymorphic appearance (different colour patterns found even in the individuals of same species). From this, again the most popular examples are to be found in the small toxic frogs of South American forests (Presented in the pic above), that appear in variety of species (there's at least three separate genera of these tiny frogs with toxic defenses). Variability in the skin colour and pattern also more generally appears typical to amphibians, as well as does the sexual dimorphism; In several cases male and female frogs exhibit rather different looks, fx. Further more, some are mentioned changing their overall skin color according to body temperatures – not quite same manner or as impressively as the chameleons, but some fx change their tones of color according the surrounding environment or frogs mood (like mentioned from the European leaf frog, Hyla arborea (LC) - also, when exposed to sunlight it appears paler by color.)

Colour patterns appear as method to warn their would-be-predators, but it's also found commonly used as camouflage by the frogs - to avoid detection from potential prey. Most frogs are carnivores - about majority eat insects but larger species also various other prey and fx typically the diet of some rain forest frogs ranges from worms and little snakes to even small mammalians (like bats, fx). To hide from their prey, certain species are found having adopted/imitating the usual background colors, even to level their skins reflecting smaller variations of litter and leaves found on the forest ground. Some horned frog species most typically mentioned examples from such adaptations. (Another interesting example, ao, we find presented in the pocket guide from East African frogs [2006]; in form of (Tanzanian) reed frog species (Hyperolius Orkarri), whose overside colours are mentioned closely matching the granite rock environment it lives at – Acc. book species is only known from few areas).

From the use of colour as warning from species palatability, there's also plenty examples at the Salamander (Caudata) families (Perhaps, not so evident of the species in pic above, Golden-striped Salamander, Chioglossa Lusitania, VU) - Salamanders and Newts form a parallel group for Frogs and Toads, the Newts being (in general) more accustomed to watery environments and Salamanders usually more terrestrial, except during their breeding periods. They typically are impressive from appearance and colour; An european species most renown of them, Fire Salamander (Salamandra salamandra, LC) represents very bright yellow colours. It has also interestingly given reasons for many odd beliefs in the past. According to the most usual from these, it was in the Middle Ages widely asserted capable of setting up fires by its sole presence and also (was believed) resistant to flames. According to another often mentioned anecdote, this false belief was already widespread and common during the Antique; Even to the level that Pliny the elder (23-79 A.D.) experimented it's accuracy when preparing his renown book, Naturalis Historia; - by throwing the fire salamander into flames, with expectable result of course. As noticed, that apparently didn't prevent the same false belief to persist through centuries for hundreds years afterwards.(...the underline on this added 28.08.2015) (Serves well also to show how a mistaken belief and fallacy can remain, and in time become part of the shared common consciousnes.)

But, from the real qualities of the Fire Salamander, it's fx mentioned that a lot variation appears between coloration of the individual animals. Some are almost completely yellowish, some represent only small bright dots. Many other salamanders as well represent by bright color a warning from their toxic defences (even though that doesn't completely prevent them being predated) – however, I've not checked if that the case also in genus plethodontidae, salamanders that are mostly renown from breathing only through their skin since they do lack the lungs completely. As for other interesting salamander characteristics, it is mentioned that some species - like the N. American Eastern newt (LC)(Pic below from Eastern Newt in the eft phase, adults are mentioned differing from color) - can find their routes from several kilometers distance for the watery streams and ponds they've been taken far away from. Even more, it's mentioned that they are able to use the position of the sun, with the aid of sensing polarized light to perceiving their position and using that (information) for directioning. As well mentioned, it been demostrated that they are able to detect Earths magnetic field and use that to form some kind of 'maps' from the surrounding environments - having sort of "GPS-system" of their own; ie it is noticed suggesting that the Newts nervous system maybe able to develop and store some detailed information from their living regions. (Halliday-Adler book, on p. 52). (How precisely/how well that mechanism is understood/studied, I've not checked, but there's a few researches from the subject listed at the end of this post). Actually, various animals similarly use some kind of 'compass' to make their routes and journeys, most renown are the migrating birds. Salamanders, whose plentiful families are distributed around the most continents (excluding the Africa and Australia), appear likewise threatened as the other amphibians by varying degree – 3 species are listed critically endangered, at least (Halliday Adler, p. 56-59).

Next we briefly devote also few words for other amphibian typical features, mainly on the diversity in their reproducing. First, there's this exceptional case in point in form of the South-American mouth-brooding frogs. In their case (the male) frog carries small tadpoles/froglets in it's vocal pouch, also providing nutrition them, and from where the fully developed little frogs then emerge.(Halliday-Adler, p 27-28). Mouth-brooding frogs include at least the species we find presented with the name Rhinoderma darwinii (VU) - listed so from it's observed decline in part of range, though mentioned still rather common on some places (acc. its IUCN Red list data sheet on Rhinoderma darwinii). Most frogs, however, do reproduce by their more common manner, laying amounts of eggs on water sources (which usually are fertilized externally). Especially the rain forest species, however, have developed additional strategies to their breeding and protection of the juvenile.

A manner used by many from tree frogs is to deposit eggs on vegetation/leafs overhanging the water, (also typical to the reed frogs, a group in the African arboreal frogs with over 120 species)(Spawls-Howell-Drewes 2006, p 184). The eggs later drop for the water where the tadpoles then start their metamorphose (for a frog). There's also species whose eggs are developed in certain 'foam-nests'. When the edges of the nest dry it falls for waters below. The inner in the foam nest remains moist some days, allowing the tadpoles to emerge in it. In some cases the creation of the foam nests involves lot group-behavior by frogs, the foam released by female frog(s) and forming the nest between leaves, which is then 'hardened' from it's outer surface by several male frogs hangin' on beside nest's edges.

Further more, there's as well many that use some alternative method like depositing them eggs in the burrows dug near the edges of the seasonal (water) pools - after the rainwater floods for pools and finally enters burrows, tadpoles swim for the open water.

(Like in the exemplary case from (East-)African Guinea Snout-burrower, interesting looking species from genus we find provided with the name hemisotidae, mentioned at Spawls-Howell-Drewes (2006) book). (Species pic above)

Somewhat more especial, may appear the reproduction of some of the earlier mentioned tiny (S. American) Poison dart frogs (from genus Dendrobates), species that live mostly within the leaf litter on level of the rain forest floor. Fx, in the case of some of the Strawberry poison frogs (D. Pumilio, LC), the frog first lays its eggs on leaves and carries the hatched tadpoles (under the protective foil on frogs back) to the axils of certain plants, or, to cloaks of trees in some cases. These contain small level of water in which the tadpoles grow to small froglets (number of other species also live in these aquatic micro-environments). The female frog also feeds tadpoles with the unfertilized eggs. Some Madagascar frogs are mentioned with somewhat resembling manner at their reproduction and 'parental care'.(Halliday-Adler 2002, p 28-29) Yet, further another exceptional method (in the variety of frog breeding) is maintained by some another South-American species that we find presented as 'Marsupial frogs', or Rana marsupial (Gastrotheca ovifera, EN). In that case eggs are first directly fertilized and each is placed to a certain protective 'pouch' on females back, where they remain in moist and pretty safe until emerging as fully developed froglets from there - and the juveniles when 'born' seem to bop directly from the frogs back. The species also is mentioned endangered acc. it's IUCN listing (IUCN Red List data sheet; Gastrotheca ovifera). Various other frog species carry their fertilized eggs on the adults back (/or, fx attached beside frogs legs like the Midwife-toads). Most usually the developed tadpoles are just dropped for water to develop. (I guess this variety of frog breeding methods only presented by brief look for the topic in above sentences... but, seems quite adequately covered, so let's leave it for that now.)

Finally, this kind of gallery of frog wonders and especial features cannot do without mentioning the 'flying frogs'; A species group comprising from the Asian (arboreal) forest frogs, that glide long distances (from tree to another) with particularly developed formations in limbs (webbings, spread for like parachutes/gliding surface, that 'permit the kermit' for “fly”, very seemingly) Among these we find a species provided with name Rhacophorus nigropalmatus (LC); or Wallace's flying frog after A.R. Wallace, 19^th century naturalist explorer also presented in our recent post. (The Indo-Malaysia islands Wallace journeyed contain various animals first recognized by Wallace and therefore named after him ; from the birds most renown are probably the Moluccan Megapode (Eulipoa wallacei, VU) and a paradise birds species Wallace's Standard Wing (Semioptera Wallacei). He also describes both quite thoroughly in the book.) For the flying frog(s) Wallace also devotes a few paragraphs, though far less in lenght than descriptions from the above mentioned species - But, it wouldn't feel too surprising if some frog species would also be named after him. In overall the Rhacophorus frogs belong for the Afro-Asian tree frogs, and in addition to this example mentioned genus/group contains number of other glider frogs. Recognized as separate species only later, perhaps. (Pic below; Wallace's flying frog)

But, for now we'll have to cut this in brief, since this only was meant to present some ordinary examples from that variety and overwhelming richness of life - From the amphibians in their about 6300 recognized species in existence worldwide and some even mix together and/or are not clearly differentiated from near similar/co-species. Many of them vulnerable to various threats, Climatic Changes the most often mentioned of those. Anyone can also easily search further details from the mentioned few species we were able to present in this (and from various other; fx, nothing we were having time or space to present from the vocal communications of the frogs, or about some other things - like from the species especially adapted for watery environments/lifes; the leaps and bounds of the frogs; not much anything from most of the popular families – like the arboreal tree frogs of the Central-/South Americas noticeable from them slender and curious looks, and most often presented in the natural books pics...And whatever else has recently been researched from amphibians and their evolutionary histories, obviously.)

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Note:

1. Species also presented with the CR listing, since both seems been moved to the category/status of EX rather recently. (In the IUCN fact sheets listed as extinct about the turn of the century. But, what a happy surprise it would make if some surviving specimen/individuals still would turn out to be found, somewhere, even that it seems very unlike possibility.)

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Sources/other information:

La Marca - Manzanilla 2004. Gastrotheca ovifera. In: IUCN 2009. IUCN Red List of Threatened Species. [Version 2009.2.] <www.iucnredlist.org>. Downloaded on 19 November 2009.

Ed Meyer (et al) 2004. Rheobatrachus silus. In: IUCN 2009. IUCN Red List of Threatened Species.[Version 2009.2.] <www.iucnredlist.org>. Downloaded on 19 November 2009.

Jean-Marc Hero (et al) 2004. Rheobatrachus vitellinus. In: IUCN 2009. IUCN Red List of Threatened Species. [Version 2009.2.] <www.iucnredlist.org>. Downloaded on 19 November 2009.

Carmen Ubeda (et al) Rhinoderma darwinii. In: IUCN 2009. IUCN Red List of Threatened Species. [Version 2009.2.] <www.iucnredlist.org>. Downloaded on 21 November 2009.

Halliday, T. -Adler, K., (2002), The New encyclopedia of Reptiles and Amphibians. N.Y.

Spawls-Howell-Drewes, (2006), Pocket guide to the Reptiles and Amphibians of East Africa. London.

Magnetoreception at (some) amphibians;

(Both studies from The Journal of Experimental Biology)

Brassart, J [et al], 1999, Ferromagnetic material in the eastern red-spotted newt Notophthalmus viridescens., (JEB) Vol 202, Issue 22 3155-3160

Phillips, John B. [et al], [2002] `Fixed-axis' magnetic orientation by an amphibian: non-shoreward-directed compass orientation, misdirected homing or positioning a magnetite-based map detector in a consistent alignment relative to the magnetic field? , (JEB) 205, 3903-3914

[ Pics at the text from Halliday-Adler book; except the Guinea-Snout burrower from Spawls-Howell-Drewes.]

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