The genus Brookesia contains some of the smallest-known reptiles on the planet, and they are leaf-litter specialists. Due to their diminutive size and the habitat in which they are found, these chameleons are very difficult to locate. Undoubtably, there are more species of leaf chameleons awaiting discovery, and perhaps there are even smaller Brookesia awaiting discovery. More via BBC:
The research team, led by Dr Frank Glaw from the Zoologische Staatssammlung in Munich, have a specialist knowledge of Madagascar’s dwarf chameleons having described other species in the past.
They conducted fieldwork at night during the wet season in order to find the easily overlooked animals.
“They mostly live in the leaf litter in the day… But at night they climb up and then you can spot them,” said Dr Glaw, explaining that the animals moved up into branches to sleep.
The scientists carefully scanned the most likely habitats with torches and headlamps to find roosting sites.
They found the smallest species on a remote limestone islet and believe it may represent an extreme case of island dwarfism.
This phenomenon occurs when a species becomes smaller over evolutionary time in order to adapt to a restricted habitat such as an island.
According to Dr Glaw there could have been a “two-island effect” in the case of B. micra.
“It is possible that the big island of Madagascar has produced the general group of dwarf chameleons and the very small island has produced the tiny species,” he told BBC Nature.
Here’s an adorable video of an orphaned short-tailed fruit bat, affectionately named Lil’ Drac, that’s being hand-raised at the Bat World Sanctuary:
Why was Lil’ Drac abandoned by his mother?
Lil’ Drac is an orphaned short tailed fruit bat (Carollia perspicillata). His mother was yet another casualty from zoo closures which are occurring across the US. Sheis a young mother who was stressed from the conditions in which she was kept, combined with the additional trauma of being captured and transferred to a new and unfamiliar environment. Consequently, she abandoned Lil’ Drac after he was born. He was found on the padded floor of the indoor flight enclosure at Bat World Sanctuary, curled up in a little ball.
You can keep up with Lil’ Drac’s progress here, and you can sponsor a bat in need here.
Here are some interesting videos of nature, science, and other things that you might’ve missed over the past few weeks:
Video: Oklahoma earthquake causes birds & bugs to take flight:More via the National Weather Service:
An earthquake whose magnitude is initially set at 5.6 by the United States Geological Survey… occurred in central Oklahoma near Prague at 10:53 PM CDT, on Saturday evening, November 5th. This animation shows how some evidence of the earthquake was even seen by radar, as birds and bugs were detected taking flight to escape the shaking on the ground. Thanks to NWS Lubbock for first bringing this to our attention.
Video: 1,500 year old sequoia falls, igniting debate:
Video: A surfer is almost swallowed by a humpback whale:
A hawk moth (Manduca sexta) feeds by hovering in front of flowers and slurping nectar through a proboscis, basically a body-length straw. To understand how these moths keep such a precise position in the air, Tyson Hedrick, a biomechanist at the University of North Carolina at Chapel Hill, tried destabilizing moths in a variety of different ways and tracked their responses using high speed cameras.
Sadly, however, gastric-brooding frogs are probably extinct. Their unusual mode of reproduction is known only from some photographs or written accounts of observations, so the chance exists that no other living human will be able to witness one of nature’s most extraordinary events. I don’t believe that video exists showing the female frogs give birth through the mouth. However, if you know of video, then please share the information.
The reason(s) for the disappearance of this species remains unknown (Tyler and Davies 1985b). Populations were present in logged catchments between 1972 and 1979. Although the species persisted in the streams during these activities, the effects of timber harvesting on this aquatic species were never investigated. Its habitat is currently threatened by feral pigs, invasion of weeds (especially mistflower Ageratina riparia), and altered flow and water quality due to upstream disturbances (Hines, Mahony and McDonald 1999). However, from what is known from similar declines and disappearances elsewhere in the world, the disease chytridiomycosis must be suspected.
However, a new, efficient automated system, which seems to be exceptionally accurate, may locate any gastric-brooding frogs that might still be in existence by listening for them. Via ABC Science Online:
Citizen science and computer software are being harnessed as a low-cost way of tracking Australian native bird species in order to monitor environmental change.
The Queensland University of Technology software is also being used on the frontline in the battle to stop cane toads marching on to Groote Eylandt in the Northern Territory.
The program uses automatic acoustic sensors, voice recognition technology and expert birdwatchers to reduce the number of hours ecologists have to spend in the field observing wildlife.
Researcher Jason Wimmer, a PhD student, says experiments show the automatic system is actually more effective in capturing the presence or absence of birds than standard observation.
Under the project, sensors are placed in the bush to record environmental sounds that are then transmitted to an online digital library.
To overcome the need to sit through hours of recordings to listen for bird sounds, Wimmer and his team developed a software program to filter the audio and identify potential bird noises.
. . .
Wimmer says the potential of the automatic system was highlighted by a 2 am recording of the call of a rarely sighted species, Lewin’s Rail (Lewinia pectoralis).
“That is just one example of the impact this system can have,” he says.
The system is also going to be used to find the Gastric Brooding Frog, a native frog that has not been seen for 20 years with sensors to be placed in the Conondale Range, north-west of Brisbane.
Wimmer says the technology is also helping protect native quolls on Groote Eylandt from eating cane toads. The island is currently free of cane toads.
“We’ve put in sensors as an early-warning system for cane toads,” he says. “The sensors are all 3G (mobile phone)-based and timed to record and analyse data automatically.”
The sensor turns on every 30 minutes and if it hears the distinctive canetoad calls is programmed to send SMS alerts to various people.
To prevent digestive juices from destroying the eggs and tadpoles, both the eggs and tadpoles produced or were associated with a “substance [that] had the ability to turn off the production of hydrochloric acid in the [frog's] stomach.” After some time, developing within their mother’s stomach, fully-formed froglets emerge from the mother’s mouth (though some accounts note that one of the species gave birth to tadpoles — not fully-formed froglets). More on the reproductive habits of Rheobatrachus silus via the IUCN:
Females brood young within the stomach and give birth through the mouth (Tyler and Carter 1982). Fertilized eggs or early stage larvae are presumably swallowed by the female and complete their development in the stomach (Tyler and Carter 1982). The number of eggs in gravid females (approximately 40) exceeds the number of juveniles found to occur in the stomach (21-26) (Tyler 1989). It is not known whether or not the excess eggs are digested by the female or whether or not they are simply not swallowed (Tyler 1989). The production of hydrochloric acid in the stomach of the female ceases during brooding (Tyler et al. 1983). Tadpoles develop in a manner similar to the aquatic tadpoles of other species though, as they feed off egg yolk, the labial teeth are absent and the intestines form at a later stage of development (Tyler 1989). After 6-7 weeks the females give birth to up to 25 young (Tyler and Davies 1983a). Young emerge from the female’s mouth as fully formed frogs and after four days the digestive tract returns to normal and the female recommences feeding (Tyler and Davies 1983b). Ingram (1983) reported minimum brooding periods from two individuals of 36 and 43 days and suggested that the duration was such that females were unlikely to breed twice in one season.
More on the reproductive habits of Rheobatrachus vitellinus via the IUCN:
It is an aquatic species largely restricted to the shallow section of fast-flowing creeks and streams in rainforest. It is one of only two known species to brood its offspring within its stomach. Females deposited their eggs, and then swallowed them. While in the stomach, tadpoles excreted some form of enzyme that inhibited the female’s gastric digestion, and then proceded to develop into fully formed froglets. The froglets were then regurgitated through the female’s mouth.
In the gastric brooding frogs, Rheobatrachus silus and Rheobatrachus vitellinus, brooding of eggs and/or larvae occurs in the stomach of the female; in one species, froglets emerge after metamorphosis, whereas in the other species, tadpoles are released by the female. Development in those frogs is supported entirely by yolk contained in the eggs (Crump, 1995; McDonald and Tyler, 1984). In contrast to Rhinoderma rufum, male Rhinoderma darwinii brood their tadpoles in their vocal sacs until metamorphosis occurs (Crump, 1995).
I couldn’t find information on whether the females of either species of gastric-brooding frogs stop feeding during gestation. However, it seems that more eggs were typically produced and swallowed than the number of froglets that were actually hatched or regurgitated by the female, so either the females digested some or all of the eggs, or the tadpoles and froglets consumed some or all of the unfertilized eggs while in the stomach, or perhaps some combination of both behaviors existed. There must have been some mechanism in place to utilize or dispose of unfertilized or bad eggs. Perhaps, the tadpoles practiced cannibalization as well. Tadpoles are known to practice cannibalism.
Video (this video plays automatically): In this video, a Southern gastric-brooding frog swims about a tank, and there’s a still image showing a froglet in adult’s mouth. Via ARKive
However, one species of frog, still in existence, uses a somewhat similar mode of reproduction to the gastric-brooding frogs of Australia. Darwin’s frog (Rhinoderma darwinii) is a species that’s “endemic to the austral forest of Chile and Argentina.” The species is considered vulnerable, and its population is in decline. Via the IUCN:
Recent surveys within the range of Rhinoderma darwinii in Chile reveal that some populations (including those in national parks and other preserved areas) have disappeared entirely (M. Crump and A. Veloso pers. comm.). In other areas, the density of frogs is much lower than 10 or 20 years ago (M. Crump pers. comm.). Forestry operations have destroyed large areas where northern populations were found. However, it was still abundant in at least some southern Chilean localities in 2003; indeed, it appears that the species reaches its highest densities in regions of the Archipelago, where habitat disturbance is minimal (M. Crump pers. comm.). In Argentina, this is a scarce species and appears to have declined at one site (Puerto Blest, Río Negro Province) during the past 50 years.
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In the north, the main threats are drought and pine forestry, while in the south it is clear-cutting of forest. Declines that have taken place in suitable habitat could be the result of other threats, such as climate change or disease (possibly chytridiomycosis, although this normally impacts species that are associated with water, and it has not previously been reported from Chile).
This species of frog exhibits a highly unusual form of parental care in that the tadpoles spend part of their life developing in the vocal sac of their father, where they ‘hitch a ride’ to a pool of water in their father’s vocal sac where they complete their development from the tadpole to the frog form.
Video: In this video, it’s possible to see the movement of tadpoles within the vocal sacs of the Darwin’s frog.
Video (this video plays automatically): A male Darwin’s frog releases fully-formed froglets from his vocal sac. Via the BBC.
Brookesia is a genus of chameleons endemic to Madagascar. Recently, the smallest-known species of Brookesia was described — Brookesia micra — and it “reaches a maximum length of just 29mm.” It is known “only known from two sites . . . on the small island of Nosy Hara, northern Madagascar.”
