alt Hacker NewsSo, they actually look like that as in the first video (gliding ribbon-like thing)? I can't tell if it's an animation or not, but it's so cool!
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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.
> So, they actually look like that as in the first video (gliding ribbon-like thing)?
It's real, and that's a real video, but it's a very weird, very atypical ctenophore.
https://en.wikipedia.org/wiki/Venus_girdle
The "Venus's girdle" is a long thin flat belt-shaped thing, but it is not wormlike. It has no head, no sense organs or anything, and the "mouth" and other main organs are in the centre of the belt, not at one end like a worm or a snake -- or you.
Most ctenophores are called "comb jellies"; one group is named "sea grapes". They are hard to generalise and not all are like this by any means, but most tend to be small, and egg-shaped, possibly with protrusions. Most tend to have 2 long trailing tentacles they use to catch food.
Most don't have muscles. They swim using bands of cilia,which are the same fine hairs that unicellular organisms use to swim, and that line your bronchi and throat. Your body uses cilia to propel mucus out of your lungs and up to where you can cough it up.
Comb jellies' cilia are in long lines, usually 8 rows. They move like a Mexican wave in a sports crowd. The light refracting through these near-microscopic beating hairs looks like they flicker with rainbows. Thus the name, comb jellies. They are often radially symmetrical along the line from mouth to other end.
That's all they have; no legs, no fins, no eyes, no dedicated sense organs. Most are not bioluminescent, but like I said, there's pretty much nothing you can say about comb jellies that applies to all of them. One type is an internal parasite that looks like a worm, although internally it's nothing like a worm. (That one is not 2-way symmetrical like us and most animals; it's four way symmetrical. It is alien compared to all other wormlike things.) Other parasitic ones are just small branching bags that don't move.
They are about the only multicellular animal that swims with cilia. They are so unlike all other multicellular animals it's just about possible that they evolved the whole plan of being multicellular entirely independently.
They look like jellyfish but are nothing like them.
Jellyfish have lots of tentacles; those comb jellies that have them, have 2, no more, no less. The tentacles don't sting; they are sticky, and the animal catches tiny plankton this way and pulls them up to its mouth to eat.
One type, Beroids, have a mouth they can close, and they can actually swallow other smaller jellies (comb jellies or jellyfish). Their lips zip shut from the edges and they have more cilia inside to propel the prey down their "throat," but they can't chew.
Some have muscles and can flex and move. Some but not many sort of swim this way, like the Venus's girdle. A very few stick to the bottom and stay there.
Comb jellies tend to have a front end and a back end, but most have no anus, just 1 hole; any food waste is vomited. But, rather wonderfully, some form an anus only when they need to poop and then it closes up again, "heals" shut, totally gone.
https://www.livescience.com/64956-ctenophore-sometime-anus.h...
They are just wonderfully weird.
They are not really alien; their genetic code is the same as ours, although they don't do things all other animals do. For example their nerves do not have synapses, so they don't need neurotransmitters to carry signals across the joins between nerves. They don't have joins. Their nerves are a continuous mesh, with long lines of cytoplasm dotted with nuclei, not divided up into separate cells -- the same sort of structure as most fungi, but flexible.
I think they are beautiful. Little was known about them when I did my biology degree, but I got into them about 5 years ago and read a lot about them for a while. They are like nothing else. Even the parasitic ones, while kind of nasty, are deeply weird.
I never saw a “Venus girdle” myself while diving, I saw some little boxy ones though, in relatively shallow water, catching the sunlight.
So I can’t vouch for that first video, but I can vouch for the rippling rainbow cilia (scroll down to the second video on that page), they really do look like that IRL.
They’re very pretty.