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By Susan Milius
may be sponges
Australian rocks contain signs
of oldest multicelled animals
Fossils of what might be ancient marine
sponges were found between mounds
(shown) of fossilized bacterial mats.
wishbones, rings and belt buckle–like
forms that Maloof calls perforated slabs.
The researchers developed software to
make a 3-D image based on hundreds of
scans of a rock surface as it is ground down
about 50 micrometers at a time. Trezona
samples showed irregular lumps shot
through with a network of fine channels
that opened to the outside. “The absence
of symmetry and the internal canal
system strongly suggests that they are
fragments of sponges,” Summons says.
Molecular-clock evidence does predict
that sponges lived during this period, says
molecular paleobiologist Kevin Peterson
of Dartmouth College in Hanover, N.H.
But he says he is not convinced that the
lumps really are sponges.
‘Whispering’ gives bats advantage
Quieter echolocation allows closer approach to eared moths
By Susan Milius
In a long-running war between bats and
moths, at least one bat has gotten the
Western barbastelle bats in Europe
typically ping out echolocation calls
softly enough to locate a moth for dinner
before the moth hears the predators com-
ing, says Holger Goerlitz of the University
of Bristol in England. It’s the first docu-
mented case of a bat species outwitting its
prey by quiet stealth, he and his colleagues
report online August 19 in Current Biol-
ogy. The battle between bats and moths
has become a classic system for studying
the evolution of predators and their prey.
Researchers set up a microphone array
where bats swooped by at night. Differences in the time it took for calls to reach
various microphones let researchers figure out barbastelles’ positions for each of
nearly 200 calls. This array helped answer
whether a barbastelle’s echolocation was
soft enough for stealth attacks.
The scientists restrained moths along
the bat flight alley and recorded activity
of their auditory nerves. A European bat
with louder echolocation, at 127 dB, triggered the moth’s auditory nerves from
about 30 meters away. A barbastelle’s
pings didn’t register until it was within
3. 5 meters — close enough for the barbastelle to have already detected the moth.
from top: A. mAloof; mAloof lAb, Situ Studio