(photo credit: Hebrew University)
A black and green frog with orange and white splotches was the first amphibian to
have officially been declared extinct by the International Union for
Conservation of Nature (IUCN) in 1996; it was thought to have disappeared after
Hula Lake dried up around 60 years ago. As a result, the opportunity to discover
more about this species’ history, biology and ecology was thought to have
But there is good news! The amphibian has been rediscovered
and has turned out to be a unique “living fossil,” without close relatives among
other living frogs.
Called the Hula painted frog, it was catalogued
within the Discoglossus genus when it was first discovered in the Hula Valley in
the early 1940s. A team of Israeli, German and French researchers now report in
the journal Nature Communications on an in-depth scientific analysis of this
The combined research effort that led to the
revelation and analyses of the “extinct” frog was conducted by Rebecca Biton, a
doctoral student of Dr. Rivka Rabinovich of the Hebrew University Institute of
Archeology, and colleagues in Israel, France and Germany. Based on new genetic
analyses of rediscovered individuals and the morphologic analyses of extant and
fossil bones, the conclusion is that the Hula frog significantly differs from
its other living relatives, the painted frogs of northern and western
Instead, the Hula frog is related to a genus of fossil frogs,
Latonia, which were found over much of Europe dating back to prehistoric periods
and has been considered extinct for about a million years.
imply that the Hula painted frog is not merely another rare species of frog but
is actually the sole representative of an ancient clade of frogs (a group with a
single common ancestor).
There are now plans to reflood parts of the Hula
Valley and restore the original swamp habitat, which may allow for expansion in
population size and a secure future for the rare amphibian.
WEATHER GOES ONLY SO DEEP
If the nightly weather report at the end of the news
were to give the temperatures and wind conditions on Uranus and Neptune, what
would that involve? As these huge planets are home to extreme winds blowing at
speeds of over 1,000 kilometers per hour, the prediction probably would be of
huge, hurricane- like storms, immense weather systems that last for years and
fastflowing jet streams. Both planets feature similar climates, despite the fact
that Uranus is tipped on its side with the pole facing the sun during
The winds on these planets have been observed on their outer
surfaces – but to get a grasp of their weather systems, one needs to understand
what is going on underneath.
For instance, do the atmospheric patterns
arise from deep down in the planet or are they confined to shallower processes
nearer the surface? New research at the Weizmann Institute of Science in
Rehovot, the University of Arizona and Tel Aviv University, which was published
recently in Nature, shows that the wind patterns seen on the surface can extend
only so far down. Understanding the atmospheric circulation is not simple for a
planet that lacks a solid surface, where Earth-style boundaries between solid,
liquid and gas layers do not exist.
Uranus and Neptune are the farthest
planets in the solar system, and there are still many open questions regarding
their formation and composition. This study has implications for revealing the
mysteries of their deep, dark interiors and may even provide information about
how these planets were formed.
Since the discovery of these strong
atmospheric winds in the 1980s by the Voyager 2 spacecraft, the vertical extent
of these winds has been a major puzzle – one that influences our understanding
of the physics governing the atmospheric dynamics and internal structure of
these planets. But a team led by Dr.
Yohai Kaspi of Weizmann’s
environmental sciences and energy research department realized they had a way,
based on a novel method for analyzing the gravitational field of the planets, to
determine an upper limit for the thickness of the atmospheric
Deviations in the distribution of mass in planets cause measurable
fluctuations in the gravitational field. On Earth, for example, an airplane
flying near a large mountain feels the slightly elevated gravitational pull of
that mountain. Like Earth, the giant planets of the solar system are rapidly
Because of this rapid rotation, the winds swirl around
regions of high and low pressure; in a non-rotating body, flow would be from
high to low pressure. This enables researchers to deduce the relations between
the distribution of pressure and density, and the planets’ wind field. These
physical principles enabled Kaspi and his co-authors to calculate, for the first
time, the gravity signature of the wind patterns and thus create a wind-induced
gravity map of these planets.
By computing the gravitational fields of a
large range of ideal planet models – ones with no wind – a task conducted by
team member Ravit Helled of TAU – and comparing them with the observed
gravitational fields, upper limits to the meteorological contribution to the
gravitational fields were obtained. This enabled Kaspi’s team to show that the
streams of gas observed in the atmosphere are limited to a “weather layer” of no
more than about 1,000 km. in depth, which makes up only a fraction of a percent
of the mass of these planets.
Although no spacecraft missions to Uranus
and Neptune are planned for the near future, Kaspi anticipates that the team’s
findings will be useful in the analysis of another set of atmospheric
circulation patterns that will be closely observed soon: those of Jupiter.
Kaspi, Helled and Prof. Bill Hubbard of the University of Arizona, who also
contributed to this research, are part of the science team of NASA’s Juno
spacecraft to Jupiter that was launched in 2011.
When it reaches Jupiter
in 2016, it will provide very accurate measurements of the gravity field of this
giant gaseous planet.