Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Young researcher discovers source of disco clams' light show

25.06.2014

Silica nanospheres behind clams' mirrored lips

Four years after falling in love with the disco clam – a cute little mollusk known for its underwater light show – Lindsey Dougherty has discovered the secret of its mirrored lips.


The disco or electric clam, Ctenoides ales, continually flashes light along the lip margins of its mantle. UC Berkeley graduate student Lindsey Dougherty discovered that the mirrored lips are composed of packed nanospheres ideal for reflecting the blue light prevalent underwater.

Credit: Lindsey Dougherty, UC Berkeley

A dive instructor and University of California, Berkeley, graduate student, Dougherty first encountered the two-inch clam in 2010 while diving with her mother and sister in Wakatobi, Indonesia. She and her sister even did a bit of underwater disco dancing to the clam's flashing beat.

"I've dived with humpback whales and great white sharks," said Dougherty, who first learned to dive at age 14 and taught diving in Zanzibar. "But when I saw the disco clam, I was enamored. I said then, 'I'm going to do a Ph.D. on the disco clam.'"

... more about:
»Indonesia »clam »dive »lip »mollusk »structure »tropical »underwater

It didn't take long for her to confirm that the flashing was not, as most people assumed, a form of bioluminescence – a chemical reaction inside animals like plankton that produces light similar to that of a glow stick. Instead, she found, the edge of the clam's mantle lip is highly reflective on one side. When the clam unfurls its lip – typically twice a second – the millimeter-wide mirror is revealed and reflects the ambient light, like a disco ball.

In this week's issue of the British Journal of the Royal Society Interface, Dougherty reports the unusual and perhaps unique structure of this mirrored lip.

The inside of the clam's lip is packed with tiny spheres of silica, only 340 nanometers in diameter, that are ideal reflectors, particularly of the blue light that penetrates deeper into seawater than does red light. The outside of the lip contains no silica nanospheres, so when the lip is furled, no light is reflected.

By repeatedly unfurling and furling the lip, the clam produces a continual rippling light show. The non-reflective back of the lip strongly absorbs blue light, so it appears dark and makes the contrast between the sides even more striking.

Dougherty used high speed video, transmission electron microscopy, spectrometry, energy dispersive x-ray spectroscopy and computer modeling to study the detailed internal structure of the margin of the clam's lip. She was assisted by colleagues Roy Caldwell, UC Berkeley professor of integrative biology; Sönke Johnsen of Duke University; and N. Justin Marshall of the University of Queensland, Brisbane, Australia. She could find no other instance of animals using silica nanospheres as flashing reflectors, though the white color of several insects apparently comes from a layer of silica that reflects white light.

The big question, Dougherty said, is why the clam flashes at all.

Called Ctenoides ales and sometimes referred to as the electric clam, disco clams are found in tropical areas of the Pacific Ocean, living in crevices in reefs and typically in clusters of two or more. Light is dim and blue-green at the clams' typical depth, which ranges from 3 to 50 meters (10-150 feet), but their rippling mirrored lips are visible even without artificial illumination. Dougherty said the question she is exploring is whether the clam is trying to attract prey, mostly plankton, or other clams and potential breeding partners; or if it is trying to scare away predators.

In ongoing experiments in Caldwell's lab, she is studying the structure of the clam's eyes – all 40 of them – to see whether they can even see the disco light. She also is raising clams in tanks to determine if they signal one another visually or chemically, and is testing their responses to fake predators.

The field work was conducted at Lizard Island Research Station in Australia and the Raja Ampat Research and Conservation Centre and Lembeh Resort in Indonesia.

Robert Sanders | Eurek Alert!

Further reports about: Indonesia clam dive lip mollusk structure tropical underwater

More articles from Life Sciences:

nachricht What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Simple processing technique could cut cost of organic PV and wearable electronics

06.12.2016 | Materials Sciences

3-D printed kidney phantoms aid nuclear medicine dosing calibration

06.12.2016 | Medical Engineering

Robot on demand: Mobile machining of aircraft components with high precision

06.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>