Pigment converts sunlight into power
The hornet’s epidermis and subcutis function like the top
and bottom electrodes of a solar cell. Between the two
layers, the hornet has a yellow pigment that functions like the
artificial pigments of a solar cell: when the sunlight affects the
pigment, the solar energy is converted into a flow of electrons.The oriental hornet has developed special cells on the surface
of its body which function like rooftop solar cells.Scientists used to think that plants and a
few bacteria were the only things that could
absorb energy directly from sunlight. But
it turns out that the oriental hornet uses
specialised cells in its exoskeleton to generate
electricity from the sun. The yellow areas of
its body contain the xanthopterin pigment,
and scientists isolated this pigment from thehornet and used it in a normal solar-cell
electrode. When the electrode was subjected
to intense light, energy was transmitted to
the pigment solution, which subsequently
generated electrical energy. The hornet’s
solar cells liberate only 0.335% of available
solar energy, so the insect has to complement
the sunlight’s energy with solid food.Hornet power! Yellow cells
work like a solar array.
Yellow cells on the abdomen of the
hornet contain the xanthopterin pigment
which converts sunlight into electricity.The Australian echidna, or spiny anteater, shares with
the platypus the status of being the only egg-laying
mammals living on dry land. But it shares something
else with the platypus — an electric sixth sense.
Free nerve endings in the echidna’s beak act as
electrical receptors to pick up the very weak electrical
signals that all living creatures generate from, for example,
nerve paths making muscles move. These enable the
echidna to locate worms, ants and termites that hide
in the ground or in rotten tree trunks. Depending on
whether it is a short-beaked or long-beaked echidna, it
may have either 400 or 2000 electrical receptors in total.Echidna’s sixth sense reveals
hidden worms and antsSnout^ regist
ers^ down^
to^1.^8 millivolts.
New cells
(^) harvest
solar (^) ener
gy.
The echidna’s receptors can pick up weak electrical
signals from creatures wriggling in the ground.
SOLAR CELL
Top electrode
Artificialpigments
Bottom electrode
HORNET
and dermEpidermis is
Yellow
pigment
Subcutis
El
ec
tr
ic
it
y Ele
ct
ric
ity
JIRI LOCHMAN/NATUREPL
KEN
IKE
DA^
MA
DSE
N^ &
SH
UTT
ERS
TOC
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64 | SCIENCE ILLUSTRATED
NATURE ELECTRIC ANIMALS