scale models of aircraft. During the experiments, the bats drank a sweet solution from
a tube dangling in front of cameras as they
hovered facing a headwind.
Laser pulses illuminated tiny liquid
droplets delivered into the airflow and
enabled the researchers to calculate the
strength and rotation of the eddies that the
bats’ flapping wings created, says Hedenström. The researchers describe their findings in the May 11 Science.
When flying at slow speeds, about
1.5 meters per second, the bats turned their
wingtips upside down and quickly flicked
them backward during an upstroke. Scientists had surmised that this trick, previously seen in high-speed movies, provides
lift and thrust, says Hedenström. By revealing vortices that signify lift, the new experiments bear out that theory, he notes.
At higher speeds, the backward flick during the upstroke disappears, and the configuration of vortices downstream of the
bat indicates a more complex airflow over
the wings. During some parts of a wing beat,
the data suggest, airflow across the inner
portions of the wing causes a force that
pushes down on the membrane there. Nevertheless, says Hedenström, the strength of
the vortices indicates that the bat’s wings,
as a whole, generate more lift than aerodynamic models suggest.
The team’s laser-illuminated experiments
“provide a beautiful look” at the aerodynamic wake behind a flying bat, says
Douglas R. Warrick, a biologist at Oregon
State University in Corvallis. “It’s the only
way to actually know what’s going on with
the airflow over a flapping wing, and even
then it’s difficult,” he notes.
It’s clear that these bats are employing
unknown tricks of aerodynamics to generate
lift, says Sharon Swartz, an evolutionary biologist at Brown University in Providence, R.I.
She and her colleagues recently reported similar findings from wind tunnel experiments
on a larger species of bat. —S. PERKINS
MOTION PICTURE The sizes of the arrows in this image indicate the speed of the airflow in
the wake of a flying bat. Blue represents clockwise circulation; red represents counterclockwise.
Every living thing will get
its own page
An international team of weighty insti-
tutions this week announced that it’s
developing the weightiest encyclopedia
of biology yet. The free, multilanguage, and videos of it “doing something inter-Web-based guide will cover the 1.8 mil- esting,” Edwards says.
lion living species known, plus new dis- The encyclopedia’s creators also say that
coveries, say researchers from the Smith- they want to supply the authority of tradi-sonian Institution, Harvard University, tional print volumes. Scientists will approve
the Field Museum in Chicago, and other certain content, and viewers will have the
organizations. option of filtering out entries that haven’t
The John D. and Catherine T. MacArthur been revie wed.
Foundation is putting up $10 million for The prototype pages ( http://www.eol.org)
the project, and the Alfred P. Sloan Foun- show that viewers may also set the level of
dation is adding $2.5 million. If the proj- complexity they’ll encounter. On a polar
ect meets its goals for the next 2.5 years, bear page, a “novice” setting reveals basic
those foundations will biology suitable for a school
repeat their grants. Also, report. Meanwhile the
the six institutions that “expert” viewer will find—
started the project have from an original 1774 doc-pledged to raise $50 mil- ument—Constantine John
lion for the work. Phipps report that “feamen”
The Encyclopedia of exploring the Spitsbergen
Life (EoL) will combine islands of Norway ate bear
the authority of a tradi- meat but found it “exceed-
tional print behemoth ing corfe.”
with the collaborative Easing access to such lit-spirit of the Web’s user- erature could help taxono-created Wikipedia, says mists in the “tedious” parts
James Edwards, EoL’s of describing species, says
Washington, D.C.–based David Patterson, a taxono-executive director. In the mist and biodiversity-Wiki spirit, EoL will even- MEET HAIRY A prototype informatics specialist at
tually have a section invit- page for the Encyclopedia of the Marine Biological Labing contributions from Life enables viewers to browse oratory in Woods Hole,
everyone, says Edwards. information about the recently Mass., an EoL partner.
At first, the creators will discovered Yeti crab. Eventually, Collecting descriptions of
take information from readers will be able to add their related organisms for
established scientific data- own comments. analysis sometimes takes
bases and present it in the years. Patterson adds that
EoL format. As the project grows, says he hopes EoL will encourage taxonomists
Edwards, bird-watchers will be invited to to use electronic tools.
record their sightings, and gardeners will Eminent biologists such as E.O. Wilson
contribute the first dates for blooms. have been calling for a grand encyclopedia
The EoL team is planning to offer spe- of life for years, but Patterson says that only
cial tools to school classes studying their recently have new Internet tools made it
neighborhoods. Combining all sources, a feasible. The first pages should be available
species’ entry might include its genetic in 2008, and the 1.8 million basic entries
sequence, recordings of noises it makes, could be online as early as 2017. —S. MILIUS