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 Bolstering fat cells offers potential new leukemia treatment
17.10.2017 | McMaster University

nachricht Ocean atmosphere rife with microbes
17.10.2017 | King Abdullah University of Science & Technology (KAUST)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>