Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A whole lot of shaking goin’ on triggers early hatching in red-eyed tree frogs

10.05.2005


Embryos distinguish vibrational differences, hatching early to snake attacks but not to rain

At the edge of Ocelot Pond, Panama, red-eyed tree frog embryos still in their eggs are about to make a life-or-death decision. The egg clutch, a gelatinous blob clinging to a leaf overhanging the water, has been spied by a bright green parrot snake. In a twinkling, the snake tears a few eggs from the clutch.

With that bite, the embryos start to wiggle frantically. As the snake moves to take another morsel, the embryos rupture their egg capsules, drop into the water, and, as tadpoles, swim away to safety -- hatching one to three days earlier than they would have if left undisturbed.



What cues prompt the embryos to hatch early when shaken by a hungry reptile but not when buffeted by another outside force such as rain, is a question that has now been answered in part by Boston University researcher Karen Warkentin. According to her findings, reported in an upcoming issue of Animal Behaviour, it’s a particular characteristic of the vibrations that shake the clutch -- not only the speed of these vibrations, or how hard the clutch is shaken, but the length of and time between the movements that signal the embryos to hatch.

Undisturbed, red-eyed tree frog eggs usually hatch six to eight days after fertilization, but can hatch up to 30 percent earlier if attacked by animals such as snakes or wasps.

At her open-air laboratory at the Gamboa Field Station in Panama, part of the Smithsonian Tropical Research Institute, Warkentin, an assistant professor of biology at BU, used parrot snakes and cat-eye snakes, to find which vibrational cues red-eyed tree frog eggs use to trigger early hatching.

By inserting a minature accelerometer, a device like a microphone that records vibrations instead of sounds, into clutches of eggs she had collected, Warkentin was able to record vibrations that occurred when the snakes attacked the eggs. As comparison, she also recorded the vibrations of the clutches caused by tropical rain storms.

To determine whether the frog embryos were hatching in response to vibration and not to some chemical or visual cue, Warkentin played the recordings back through a device that mechanically shook the clutches. Sure enough, the eggs hatched more often in response to snake-attack recordings than rainstorm recordings.

"They hatch when the snake starts biting the clutch, not before," she says. "It’s not because there are snakes in the neighborhood or snakes there looking at it."

Warkentin examined the recordings to see whether she could tell how rain and snake-attack vibrations differed. "Two of the most obvious differences between vibrations caused by rain and vibrations caused by snakes are elements of the temporal pattern," she says. "Snake bites, in general, last longer than raindrops, and the spaces between snake bites are generally longer than the spaces between raindrops."

To test the hypothesis that embryos use these features of vibrations to assess danger, Warkentin clumped the rain recordings together into tightly spaced segments, making them more snake-like. Conversely, she spliced bits of stillness into the snake vibrations, making them more rain-like. When snake-like rain and actual rain recordings were played to a clutch of red-eyed tree frog eggs, the eggs hatched more often to the snake-like rain recordings. When the rain-like snake recordings and actual snake recordings were played to the clutch, the embryos hatched less often in response to rain-like snake recordings. Both instances, therefore, provided more evidence that temporal patterns serve as an important cue for the frogs.

Warkentin created similar temporal patterns out of computer-generated nonspecific sound, or "white noise." Again, the snake-like pattern of white noise caused more eggs to hatch prematurely than did the rain-like white noise. "These experiments don’t rule out the possibility that the frog eggs use other cues," she says. "But clearly, differences in temporal patterns are enough to affect the perception of how dangerous a disturbance is."

Ann Marie Menting | EurekAlert!
Further information:
http://www.bu.edu

More articles from Life Sciences:

nachricht The dense vessel network regulates formation of thrombocytes in the bone marrow
25.07.2017 | Rudolf-Virchow-Zentrum für Experimentelle Biomedizin der Universität Würzburg

nachricht Fungi that evolved to eat wood offer new biomass conversion tool
25.07.2017 | University of Massachusetts at Amherst

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>