Pyrosoma
This week’s Sunday Stills challenge theme is ‘Fifth.’ (See more offerings here.) I was stumped as to what to post until I thought about looking back to see what photos I’d taken on the fifth of a given month. As it happened, these somewhat strange photos were taken just one month ago, on April 5th, and I was now ready to run them.
I was out snorkeling and was drawn to some black triggerfish, which were gathered in a very tight group. I took some photos and as I maneuvered around the group I became aware of something very close by.
The thing was at least two feet long and six inches or so in diameter. It was translucent, but with short lines of purple dots, and a milky central line through the tube. It was floating just below the water, changing shape, though not appearing to propel itself, but more being moved by the water. I thought it was some kind of egg sac, but really had no idea what it might be.
I wasn’t even sure I could get a photo of it, since I thought my camera might not ‘see’ it and instead focus on the fish beyond. I was also leery of getting too close. Perhaps it was some form of jellyfish or some other creature loaded with toxins.
When I got home, I was thrilled to find that some of the photos had turned out and registered what I’d seen, but I had no idea what it was. It didn’t really look like an egg sac, but what were the alternatives?
I had a browse in John Hoover’s Guide to Hawaii’s Marine Invertebrates and the closest thing I found was a prickly pyrosoma (pyrosoma atlanticum), but while the general shape was similar, the surface looked much less smooth than the thing I saw. So I shared the photos with some local snorkelers and divers and asked if they had any idea what it was. A couple of ideas were floated but nothing definitive. No one had seen anything like this before.
I looked online and found a few images that bore some resemblance. One of those links was to John Hoover’s website so I thought, ‘Why not ask someone knows about these things?’ and sent him an email with the photos. He quickly responded that it looked like a pyrosoma, a type of tunicate, and referred me to the listing in his book.
As we exchanged emails about a definitive identification, he noted, ‘Often microscopic examination is required to definitely identify tunicates, so unless you can get a piece of one, preserve it properly, and send it to a specialist we’ll probably never know exactly what it is.’
So what is this pyrosoma in the photos? Well, the name means ‘fire body’ and it can light up at night. It’s a colonial tunicate that can be 30 feet or longer (search online for pyrosoma and diver to see examples). Tunicates are filter-feeding creatures that either attach to hard surfaces or float free in the oceans. The colony is made up of zooids, individuals animals that are embedded in a gelatinous tube, which is open at one end and, apparently, is quite hard to the touch. One end of each zooid opens to the outside of the tube, the other end to the inside. Each zooid filters tiny cells from the water outside and expels filtered water to the inside of the tube.
Now, every time I get in the water, I’m looking around for another one. I probably won’t see one, but if I do get lucky, I just want to poke it, gently of course, to see what it feels like.
The photos show the shape and general composition of the pyrosoma. Some people have said it must have been huge because it dwarfs the fish in the photos, but the pyrosoma was only a couple of feet away. The fish were 20 or more feet beyond.
How incredible and interesting! The photos are beautiful even if viewed just as abstracts. Thanks for explaining the size and scale.
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Thanks. I do hope I see another one sometime as I’d have more of an appreciation of what I was seeing. As it was, I was pretty much clueless. I’m happy I got the photos though.
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So fascinating! Have never heard about anything like that!
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It was a new one for me too. I never know quite what I’ll see when I go snorkeling.
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There’s a magical world down there! Excited to read and see about your adventures 🙂
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Snow is right, aquatic aliens from the 5th element! Super cool shots, Graham, and very unusual to see. Thanks for the marine biology lesson and finding a fun post for Sunday Stills!
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It was fun doing the research and the local swimming community got involved too.
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Fascinating, though I had hoped it was an alien life form from Mars. 🙂
BTW, two ads are covering some of the text at the bottom of your post, at least on my PS screen.
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Now an alien life form would be cool. Thanks for the heads up about the ads. I’ve had that happen on my screen, too. I think it’s a problem with my theme (which is old and no longer supported) and the new blocks format (which I hate). I’m planning on changing it, but haven’t yet had the time.
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Well that looks ghostly, alien, very ”5th element” – I might even be slightly frightened to get in the water there again! (And 5th, what an interesting theme!! Refreshingly original)
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It was weird, but not scary. I didn’t really think it was dangerous, just didn’t have any idea what it was. Rather than keep me out of the water there, it makes me want to get in again in the hopes of seeing something similar.
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