A graduate student from Berkeley has discovered the secret workings of the disco clam’s previously
inexplicable light show.
Disco clams, also known as the Ctenoides ales, live in tropical
regions of the Pacific, clustering inside reef crevices. They are
known for producing flashing underwater light shows, which it has
now been discovered have nothing to with bioluminescence — the
process in which light is produced by living organisms due to a
Instead, one side of the edge of the clam’s lip is very
reflective and when it unfurls it — around twice every second –
the lip reflects any ambient light in the same a mirror ball does.
The inside of the lip is only 1mm and is packed with silica
nanospheres. The clams live at between three and 50 metres under
water where light is dim and blue-green, but the silica is an ideal
reflector of the blue light that penetrates these deeper waters, so
the light show can continue even in the semi-darkness.
Lindsey Dougherty, the researcher studying the clams, is an
experienced diver and first became interested in finding out how
the creatures performed their light show after observing them in
the wild. To discover the secret, she employed a range of
techniques including high-speed video, transmission electron
microscopy, spectrometry, energy dispersive x-ray spectroscopy and
As far as we know, no other creatures use silica nanospheres as
flashing reflectors, although several insects do appear white due
to a layer of silica in their bodies.
The next challenge for Dougherty is to work out why the clams
flash at all — whether they are trying to attract prey or breeding
partners, or maybe they are scaring away predators. In further
experiments she is studying the clams’ 40 eyes to try and deduce
whether they can see the light that they are themselves producing.
She is also hoping to discover whether they use the lights to
communicate with one another and to test their reactions to fake