ADVANCES
24 Scientific American, October 2020 Illustration by Thomas Fuchs
FROM “ARTHROPOD ENTOMBMENT IN WEATHERING-FORMED OPAL: NEW HORIZONS
FOR RECORDING LIFE IN ROCKS,” BY BORIS CHAUVIRÉ ET AL., INSCIENTIFIC REPORTS,VOL. 10, ARTICLE NO. 10575; 2020. HTTPS://DOI.ORG/10.1038/S41598-020-67412-9ANIMAL BEHAVIOR
Migration
Meteorologist
Seabirds anticipate typhoons
to help their journey
Migrating terns may alter their flight
plans based on a keen sense of approach-
ing typhoons, escaping the brunt of the
storms but still benefiting from feeding
opportunities in their wakes.
Researchers at the Yamashina Institute
for Ornithology examined data recorded
by tracking devices on six black-naped
terns from Okinawa, Japan, to learn more
about the birds’ migrations over multiple
years. The terns flew across part of the
Philippine Sea’s “typhoon highway” to get
to the islands of Borneo and Sulawesi and
varied their departure times—often appar-
ently waiting to leave until a large typhoon
was about to cross their projected path.
“They seem to be able to predict it,” says
Jean-Baptiste Thiebot, a postdoctoral fellow
at the National Institute of Polar Research
in Japan and lead author of the new study,
which was published in June in Marine Biolo-
gy. The study offers few clues about how
terns might do this, but other research sug-
gests some migrating birds detect infrasonic
weather signals or observe changing clouds.
The terns Thiebot studied typically
avoided the typhoons themselves. But
these storms can churn food to the ocean
surface, so their immediate aftermath may
help the hungry travelers. “They might
actually use the typhoon to know when toleave” for their migrations
each year, Thiebot says.
In the unusually quiet
2017 season, without
a strong typhoon cue,
the birds started their
journeys later and flew
without pit stops. Thie-
bot would like to see
this pattern confirmed
in a larger study. He also
worries that increasing
typhoon frequency could
affect birds’ prediction accu-
racy, potentially getting them
caught in dangerous weather.
Robert Gill, an emeritus research
wildlife biologist with the U.S. Geological
Survey, who was not involved in the work,
says that although the study’s sample size
is small, it adds to scientists’ overall under-
standing of migration. He has studied shore-
birds that time their migrations based part-
ly on incoming storms, but little research
has delved into this behavior. “They are
able to predict better than the best weather
forecasters we have,” Gill says, “but they’ve
also had tens of thousands, if not millions, of
years to hone that skill.” — Joshua Rapp LearnPALEONTOLOGY
Entombed
in Opal
A rare fossil hints at
records of early life
A bug trapped in a precious gem could
offer new clues in the hunt for ancient life
on Earth and Mars. The opal, pulled from
rock in Indonesia and nicknamed “Bever-
ly,” contains the shell of a tiny cicada
nymph. In June in Scientific Reports,
researchers explained how it likely formed.
Other opal fossils have been found
among silica-containing rocks that form
near geysers, says Boris Chauviré, a geolo-
gist at Grenoble Alpes University in France.
Hot water dissolves these rocks; when the
resulting silica-rich fluid cools, it can harden
to form the shimmery gem—sometimes fill-
ing in spaces left by decayed organisms or
trapping creatures’ bodies. But this fossil
comes from soil made by volcanic rocks
eroding, and it is the first animal
found en tombed in opal that
formed this way. Knowing this can
happen, Chauviré says, suggests
new places to look for ancient life.
This kind of opal formation is
in fact more common than the
hydrothermal process, but it is
slower and thus considered less
likely to preserve traces of life. But
the team found a layer of zeolite,
a silica-rich mineral, coating the
exoskeleton; the researchers’
analysis suggests that the sub -
stance crystallized on the shell while it was
buried in soil and exposed to silica-carrying
water, preserving its structure before the
surrounding liquid eventually formed opal.
“This is the first time I’ve seen this type
of preservation,” says Frances Westall,
a geologist and astrobiologist at CNRS in
Orléans, France, who was not involved in the
study. She says the viability of this process—
somewhat analogous to more common cas-
es of insects preserved in amber, a fossilized
tree resin—opens up more possibilities forfinding evidence of ancient life. “The early
Earth was a volcanic environment like Indo-
nesia,” she says. “And so was early Mars.”
“Now we know that all kinds of silica
can contain this kind of fossil or biomole-
cules,” Chauviré says. Opal fossils that
formed in volcanic settings such as early
Earth or early Mars could reveal ancient
underground critters that are not typically
preserved in sedimentary rock or amber,
he adds: “The future Jurassic Park can be
with opal, maybe.” — Carolyn WilkeHeadForelegMiddle leg Back legsThorax Abdomen1 millimeter© 2020 Scientific American