The clusterwink snail (Hinea brasiliana) is a small snail found in the ocean off Australia. It has an extraordinary property: It can produce light, blinking or flashing on and off in an attempt to distract predators.
Bioluminescence is actually quite common in small deep-sea species. Most commonly, it's used to attract rather than distract. In a cold and inhospitable environment, leaving a bright trail is a good way to notify potential mates that you're in the area. Other snail species secrete bioluminescent slime trails to do just that. The clusterwink snail operates on a different principle - it uses bioluminescence to fend off predators. That makes it unusual, maybe even unique, among snails. It's not entirely unique, though; some other more mobile species secrete small packages of highly bioluminescent material when stressed to try and confuse or misdirect a pursuing predator, akin to a military aircraft dropping flares or chaff to confuse a missile's seeker-head.
The clusterwink snail produces light in an unusual way, though. The animals described above secrete liquids that are, themselves, bioluminescent, either because they contain certain important chemicals or because they contain bacteria that, in turn, are bioluminescent. The clusterwink snail actually "flashes" its entire shell on and off. It does when it feels threatened, such as wen it has been touched or when it perceives potential predators in the vicinity.
This works through a fascinating process. The clusterwink snail only has a single light-emitting region, which flashes on and off. However, its shell is specially adapted to diffuse, or scatter, a particular frequency of bright green light. Hit with any other type of light (from an external source), the clusterwink snail's surface is an opaque yellow, much like any other snail. With the right color of green, however, the snail's body appears to light up like a frosted light bulb.
Flashing a bright light doesn't square with the more common method of avoiding predators - camouflage. However, biologists think there are two possible achievement of the clusterwink snail's light-flashing system. First, it might serve as a beacon for other, even larger predators - predators that aren't particularly interested in snails, but are interested in whatever is lurking that might want to eat the snail. Second, sudden flashing lights might serve to startle and scare off predators as they close in.
The new research into the clusterwork snail is being published in Proceedings of the Royal Society B, and may have implications for bioengineering and biotechnology research companies.