Tag Archives: Tunicates


A siphonophore in the waters off Hawaii

I was snorkeling recently when I saw this strange tubular stringy thing. That’s not a scientific term. My first thought was that it was a Chained Salp, a tunicate that is a colony of individual Salps. But this one seemed a bit different. There was the main tube, but also thinner strings hanging off it.

I started taking photos, which was a bit of a trick in the lumpy swell. I wasn’t worried about getting too close since Chained Salps are harmless. I wasn’t worried until I got too close and realized I’d been stung on the hand by some those tendrils! That was enough for me and I headed to shore.

Back at the house, I couldn’t identify it in my book so I emailed a fellow snorkeler who is well-versed in these sort of things. She had encountered these before and identified it as a Siphonophore (Thanks, Wendy.). Like the Chained Salp, this is a colony of individuals, but unlike the harmless salps, siphonophores have stinging tentacles which they use to catch prey.

Possibly the best known Siphonophore is the Portugese Man-Of-War, one of which had stung a fellow snorkeler just a few days earlier. His wounds were very painful, but I got off easily, with just red welts and a mild burning sensation for a couple of hours.

A siphonophore in the waters off Hawaii

Chained salp

Yesterday, when I was out snorkeling, I was spotted this entity hanging in the water. When I first saw it, I thought it might be a pyrosoma. I was lucky enough to see one of those last year, which I posted about here. Pyrosoma are colonies of many individual tunicates and this new sighting looked somewhat similar. But where that pyrosoma looked like a gelatinous tube with little purple dots in it, this tube was longer, thinner, and had much larger, and clearly visible, brown spots in it.

After some research, I’m pretty sure this is a chained salp. Like pyrosoma, chained salps are colonies of individuals. The individuals have a heart, gills and a spinal cord, which makes them quite advanced in evolutionary terms. They move around by pumping water through their bodies. When they form chains, the individuals in the chains communicate with electrical signals so the the chain moves in harmony.

Typically, salps are creatures of the open ocean, and not often seen in Hawaii, so I feel quite fortunate to have seen this one.


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.