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 A novel synthetic antibody enables conditional “protein knockdown” in vertebrates
20.08.2018 | Technische Universität Dresden

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Quantum bugs, meet your new swatter

20.08.2018 | Information Technology

A novel synthetic antibody enables conditional “protein knockdown” in vertebrates

20.08.2018 | Life Sciences

Metamolds: Molding a mold

20.08.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>