Join me in the cold, dark, life-sustaining NE Pacific Ocean to discover the great beauty, mystery and fragility hidden there.

Pyrosomes! Say What?

Pyrosomes – literally “fire bodies” in Greek – are weird and wonderful marine organisms that have recently been sighted in large numbers from Oregon to British Columbia’s central coast. The inspiration for their name is that, when alive, they can generate “brilliant, sustained bioluminescence” (Bowlby et al).

A beach full of Pyrosomes ©Marie Fournier.

January 24, 2017: A beach scattered with Pyrosoma atlanticum. Stunning photo by ©Marie Fournier. Location: West Beach on Calvert Island; 51°39’13”N; 128°08’27″W. 

Specifically, it is Pyrosoma atlanticum that is being seen in large numbers and about which I have been getting inquiries dating back to February of last year. More about this species later. First some general information about this genus.

As gelatinous as pyrosomes appear, they are not closely related to jellyfish. They are colonial pelagic tunicates often found in dense aggregations. Tunicates are highly evolved. They even have a primitive backbone (a notochord).

February 19, 2016 (the first  inquiry I got about this species): A single Pyrosoma atlanticum colony found and photographed by ©Tiare Boyes while diving at ~70′. It was being snacked on by hermit crabs and marine snails. Location: Just outside God’s Pocket; 50°50’15”N, 127°33’40”W.

Colonial? Yes, each pyrosome is made up of thousands of individual “zooids” that are connected by tissue (a tunic) to form a rigid, bumpy, hollow tube that is open at one end. This design allows the individuals to filter feed. Cilia draw water into each zooid where plankton are removed with mucous filters; the filtered water passes into the tube; and then out the back end of the colony. This current not only allows feeding but also propulsion of the colony.

But wait, it gets even more remarkable. The individuals making up the colony are clones. Thereby, the colony can regenerate injured and broken parts. “Unless all individual clones are killed at the same time, a colony can theoretically live forever, shrinking and growing based on available food and physical disturbance.  Individual clones are hermaphroditic; they make both eggs and sperm (Oceana).” It is hypothesized that when colonies meet, they may also reproduce sexually.

One Star Trek inspired biologist has referenced pyrosomes as the “the Borgs of the sea”. I just have to share that description with you:

 “One long pyrosome is actually a collection of thousands of clones, with each individual capable of copying itself and adding to the colony. And like members of the Borg, which are  mentally connected, pyrosome members are physically connected– actually sharing tissues. And while the Borg live in a big scary ship, pyrosomes are the big scary ship. The whole colony is shaped like a giant thimble with a point on one end and an opening on the other . . . . Each little “wire basket” is the stomach of one member of the colony. They take water in through a mouth on the outside of their space-ship body, pass it through the little basket to filter out the nom bits, and squirt water out the other end, into the big hollow space in the middle” (R.R. Helm; Deep Sea News).

“Big scary ship”? The “Giant Pyrosome” (Pyrosoma spinosum) can indeed be up to 18 long with an opening reported to be up to 2 m wide. But that is a species found in tropical waters.

The pyrosome species being sighted along the west coast is much smaller. Pyrosoma atlanticum (class Thaliacea) can reach lengths of 60 cm but as you can see from some of the images here, those being reported are much smaller, ranging from about 5 to 8 cm long. This species may be colourless, pink, grey, or bluish-green.

It is the most widespread pyrosome species. It is found in all oceans with the generally accepted range being between temperate latitudes of 50°S to 50°N.

October 1, 2016: Pyrosoma atlanticum were also being seen but much further offshore. Photo: ©Christie McMIllan. Location: About 145 km off the west coast of Vancouver Island.

Thereby, up to around mid Vancouver Island, British Columbia is part of their range but they are usually much further offshore. It is only when wind and tides wash them onto beaches that more of us get to see them. The species already generated a lot of interest much further to the south when they were getting blown ashore in Oregon from October to December 2016. They were also being sighted far off BC’s coast in October.

More recent reports on BC’s coast are beyond 52°N. This is certainly more unusual and indicative that there is likely a warm water mass carrying them further north.

December 2016 photo from ©Stan Hutchings and Karen Hansen. Location: Quigley Creek in Laredo Channel; 52°39’15”N, 128°44’05”W

For those lucky enough to see them at night, pyrosomes bioluminesce with an intense, bright, blue-green light that can apparently last more than 10 seconds. Their bright lights inspired biologist T.H. Huxley to write in his1849 journal: “I have just watched the moon set in all her glory, and looked at those lesser moons, the beautiful Pyrosoma, shining like white hot cylinders in the water.”

Pyrosoma are unique not only in how brilliant and sustained this bioluminescence is, but also because they are among the few marine organisms where light is made in response to light, not only in response to touch. Thereby, a wave of light passes from one individual in the colony to the next AND from colony to colony (Bowlby et al)! The light is believed to actually be made by bacteria living within the zooids.

Oh to see that!

But I will already be deeply content if I am lucky enough to see just one Pyrosoma atlanticum. 

I do have a good chance.  Now, while finally writing a blog in response to queries about these tubular, drifting, animals, I am on a Fisheries and Oceans Canada (DFO) cetacean survey in the area where they were recently reported in large numbers.

When I do see one, I will certainly report back to you.

In the interim, I would like to thank those who relayed all the queries and sightings. This is a solid case of how the observations, interest and knowledge of many allow a bigger picture to come together. This picture may have relevance to science and certainly has value in generating greater interest in our lesser known, wonderfully weird, light-emitting, totally tubular, marine neighbours.

A Pyrosoma atlanticum colony. ©Stan Hutchings and Karen Hansen.

Sources:

One Response to “Pyrosomes! Say What?”

  1. Anonymous

    I saw them on Calvert Island beaches in September 2016. Now I will also be looking for them at night! Thank you again for your wonderful informative articles.

    Reply

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