In episode 54 of Take a Minute to Relax, we introduce you to a rather flashy reef character: the ELECTRIC CLAM (Ctenoides ales). The underwater world is filled with many wonders. Just when you thought you’d seen it all, the ocean presents you with the electric clam. Ctenoides Ales as it is scientifically named, is a species of salt-water clam, a marine bivalve mollusc in the family of Limidae. Due to its unusual appearance, this creature has received many nicknames like electric flame scallop, disco scallop, electric clam and disco clam, just to name a few.
Light show uncovered
It is perhaps a little odd that an extravagant creature like this has been very little studied. But the one thing we do know is that it is currently the only known bivalve (a group containing clams, oysters, cockles, mussels, and scallops) in the world with its own light display. Before you assume that this is yet another example of bioluminescence, as is the case with many ocean “illuminati”, let us tell you: It is something else entirely.
Only recently has Ctenoides ales’s dazzling display been properly investigated. It turns out that instead of employing light-emitting molecules and enzymes, like certain species do to produce intermittent bioluminescence, this little creature’s flesh has a permanent glow to it. Research uncovered that the very outer edge of the electric clam’s mantle is made up of minute nano-spheres of silica, creating a highly reflective glow. By covering and uncovering, our disco clam can turn the lights on and off at will. So, the flashing light show we witness is in fact reflected sun- and/or dive light.
Why exactly Ctenoides ales evolved to wield such a flashy disco display is not entirely clear yet. However, most animals don’t do something that costs this much energy, unless they benefit from it in one way or another. Initial research into whether their flashy behaviour was perhaps a method to attract mates, has shown that their light show made very little difference in drawing in suitors. On the other hand, when these creatures were tempted with their preferred food (plankton), or were exposed to predators, the flashing increased. As an extra line of defence, this disco creature happens to contain a whole lot of sulphur in its mantle and tentacles. As one can imagine, sulphur tastes rather awful.
Ctenoides ales can be found in warm, tropical waters throughout the central Indo-Pacific region, including along the north coast of Australia. They settle at depths of up to 20 metres, tucked inside small crevices formed by rocks and other debris on the ocean floor.
This clip of Electric Clam (Ctenoides ales) has been slowed down in order to fully appreciate the light show of this gorgeous disco creature. What a wonderful world we live in!
So much more to uncover
What a beautiful world we live in! This video was filmed at one of the dive sites of Wakatobi Dive Resort in 2019.