Yep. This is their normal aspect. The ribbon species is named the "Venus belt", and the round ones are called "Sea grapes" or something like that.

And they are nor just bioluminiscent, they are strongly bioluminiscent. Cilia adds motion to the spectacle and maybe can change its color, but they definitely can turn on and off the lights. The cilia pads are used mostly for movement.

Many of this animals live in places without much light and do a vertical migration at night, each night. All are carnivores of small preys and is assumed also that they use light to lure its preys near their sticky longlines. Very abundant and probably one of the zoological groups were we could still find suddenly thousands of news species, but studying them is a nightmare. They literally melt when manipulated or in the microscope. At the sea, if they are cut the biggest chunks can regrow a whole body.

Its chemical lights can be used by us to detect toxics in the water. They react to contaminants making the luminiscence much brighter. Just as if they were alarmed and trying to warn other.

I wonder just now, if there is a hidden language there, like with bees dancing to communicate with other bees. Who knows. The problem is that they don't have eyes (If I remember correctly) so would need some other mechanism to see the lights. Maybe chemical.

Is a good example of how trying to equal how other animals experience the world with our experience is a mistake. Imagine seeing light with your tongue. This animals could even not be aware that they are bioluminiscent.