Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mystery of Funky ‘Disco’ Clam’s Flashing Revealed

05.01.2015

In the dark, underwater caves of the Indo-Pacific Ocean, a lucky diver may be treated to a rare underwater light show: the flashing of the clam Ctenoides ales, also known as the ‘disco’ clam.

How and why these invertebrates produce their spectacular display is a mystery. New research by Lindsey Dougherty of the University of California, Berkeley, suggests that scaring off predators or luring prey may be the primary motivations for the disco clam’s flashy behavior.


Lindsey Dougherty

The ‘disco’ clam Ctenoides ales sends ripples of light along the edge of its mantle to produce a flashing display, but why?

Dougherty first became fascinated with disco clams when she was shocked by their display during a dive in Indonesia. “It was on that trip I first saw the disco clam, and immediately fell in love,” reminisced Dougherty.

Upon her return, Dougherty was surprised to discover that despite their attention-grabbing behavior, it was not known why the flashing is produced. She and her collaborators, Professor Roy Caldwell and undergraduate Alexandria Neibergall, set out to investigate.

The disco clam is an active, filter-feeding mollusk that lives in crevices or small caves in Indo-Pacific coral reefs. Their flashing is so bright that it had been thought to be the result of bioluminescence, the production of light within the tissue. But deeper investigation has revealed a much more unique mechanism behind the displays.

Using high-powered transmission electron microscopy, Dougherty discovered that the flashes are caused by specialized tissues that form a double layer, reflective to light on one side, but absorbent on the other. When the tissue is rapidly rolled and unfurled by the clam, the reflecting light gives the appearance of flashing.

These tissues are so reflective that they can even flash using the low levels of blue light found in the caves. They are the only species of bivalve to have evolved structural coloration of this kind, and this latest project set out to discover why.

Dougherty and colleagues had three hypotheses about why the clams flash: to attract a mate, to scare off predators, or to attract prey. They tested these hypotheses using experiments on live clams in the lab. They wanted to know: can the clams see each other? Do they respond with flashing to other clams, predators, or prey?

They examined the structure and proteins in the clam’s tiny eyes using a powerful microscope and concluded that its vision is likely too poor to allow it to observe displays by other clams. This suggests that the clams are not visually attracted to one another, and that the flashing is most likely used for repelling or attracting other species.

Next, they tested the effect of the flashing on predators, which in the wild might be octopi, predatory snails, or mantis shrimp. For this study, they conducted ‘looming’ trials, during which the researchers moved a false predator in the direction of the clams, and gauged their reactions.

“In this case, the false predator was just a styrofoam lid. But it turns out a styrofoam lid is indeed pretty scary to the clams, because their flash rate almost doubled from just under 2 Hz to just under 4 Hz,” said Dougherty.

Intriguingly, the researchers also found high levels of sulphur, the key ingredient in sulphuric acid, in the clam’s tentacles. Additionally, a peacock mantis shrimp that was attacking the disco clam seemed to recoil from its tentacles and enter a catatonic state. This preliminary information suggested to Dougherty that the clams may be producing noxious, acidic mucus to repel predators.

Finally, phytoplankton prey were introduced into the tank. As the clam’s tentacles began to sense the presence of prey, their flash rate increased significantly. Many species of plankton are indeed phototaxic and therefore attracted to light, though it is unclear whether the disco clam’s prey species are able to see their flashing, a topic of a future field study.

Working with these clams in the wild, despite their visual appeal, also has its drawbacks. “Doing an experiment is one thing, but doing an experiment underwater, even a simple one, is exponentially more difficult,” Dougherty explains. “Coral reefs are fragile environments; you have to be very conscious of what you are doing.”

Then there are the technical issues: “Even once you do get the camera set up, I’ve had hermit crabs walk over and run into the GoPro camera and knock it over. Every day is an adventure with underwater research!”

Dougherty presented this research at the 2015 annual conference of the Society of Integrative and Comparative Biology in West Palm Beach, Florida. Video of the disco clam can be found at: https://www.youtube.com/watch?v=D_siqfXOSaA&feature=youtu.be

Contact Information
Brett Burk
Executive Director
bburk@BurkInc.com
Phone: 703-790-1745
Mobile: 703-981-7708

Katrina Jones, Harvard University | newswise

More articles from Life Sciences:

nachricht 'Flamenco dancing' molecule could lead to better-protecting sunscreen
18.10.2019 | University of Warwick

nachricht Synthetic cells make long-distance calls
17.10.2019 | Rice University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Solving the mystery of quantum light in thin layers

A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)

It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...

Im Focus: An ultrafast glimpse of the photochemistry of the atmosphere

Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...

Im Focus: Shaping nanoparticles for improved quantum information technology

Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.

Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...

Im Focus: Novel Material for Shipbuilding

A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.

The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...

Im Focus: Controlling superconducting regions within an exotic metal

Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).

Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

NEXUS 2020: Relationships Between Architecture and Mathematics

02.10.2019 | Event News

Optical Technologies: International Symposium „Future Optics“ in Hannover

19.09.2019 | Event News

 
Latest News

Energy Flow in the Nano Range

18.10.2019 | Power and Electrical Engineering

MR-compatible Ultrasound System for the Therapeutic Application of Ultrasound

18.10.2019 | Medical Engineering

Double layer of graphene helps to control spin currents

18.10.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>