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Posts from the ‘Tunicates’ category

Pyrosomes! Say What?

Pyrosomes – literally “fire bodies” in Greek – are weird and wonderful marine organisms that have been sighted in large numbers from Oregon to British Columbia’s central coast to Yakutat Alaska! 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.

Pyrosomes on salmon trolling gear.
©Dobie Lyons.

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 nearer to shore 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.

It was already unusual to see them off BC’s coast beyond 52°N in March. In May 2017, they were being reported off Yakutat, Alaska, beyond 59°N. This is extremely unusual and is indicative that there must be 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!

Thank you to 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.

 

Video by Patrick Anders Webber. 

Particularly large Pyrosoma atlanticum, 35 nautical miles off Neah Bay, Washington. In photo: Dobie Lyons. Photo by Alan Tyler.

Sources:

News:

Otherworldly Drifter. Mind Blown.

Today was the first time ever that, while diving, I made a gesture to my dive buddy indicating that my brain had exploded.

We weren’t deep; the remarkable find that had me awestruck was at 3 to 5 metre depth. It’s a known species and is found throughout the Atlantic, Pacific and Indian Oceans but  . . . . it’s certainly extremely rare here around NE Vancouver Island and it is SO otherworldly.

Let me take you on a short journey of discovery.

I was already pretty excited when I found the organism in the photo below. I knew it to be a salp “aggregate” and was delighted that there was an amphipod hitchhiker. See it?

Cyclosalpa bakeri with amphipod hitchhiker ©Jackie Hildering; www.themarinedetective.ca

Cyclosalpa bakeri with amphipod hitchhiker.
©Jackie Hildering; http://www.themarinedetective.ca

Salps are such unique gelatinous animals! They belong to the group of highly evolved invertebrates known as tunicates. Most tunicate species live attached to the bottom when they are adults but salps remain Ocean drifters for their whole lives. Because of their gelatinous “tunic” they have even been referred to as Ocean Gummy Bears.

Their reproduction is totally otherworldly! They alternate between two forms. The image above is of the “aggregate” form or “salp chain” that, dependent on species, can be made up of millions of individuals. The aggregate form reproduces sexually to form a barrel-shaped solitary form. The solitary form buds off (asexually) to produce the individuals that make up the aggregate form and so on! Salps apparently grow faster than any other multicellular organism! (Source: JelliesZone).

Back to the dive  . . . so I was already pretty thrilled to have seen the salp chain of this unique species and was taking the photo below of an Alabaster Nudibranch (because you can NEVER have enough photos of Alabaster Nudibranchs)  . . . .

Alabaster nudibranch. Dirona albolineata to 18 cm aka “white-lined dirona” or “frosted nudibranch”. ©2015 Jackie Hildering

Alabaster nudibranch. Dirona albolineata to 18 cm. ©2015 Jackie Hildering

. . . . and then I saw something hovering above me, zeppelin like.

Brain exploded. WHAT was this?!

Pelagic tunicate. Salp species - Thetys, solitary phase. To 33 cm. ©2015 Jackie Hildering

©2015 Jackie Hildering

It was about 25 cm long.

It had openings on both ends.

It clearly had internal organs.

And it had unique projections on what I assumed was its back end.

The look on my dive buddy Natasha Dickinson’s face in the image below says it all!

Dive buddy with Thetys. ©2015 Jackie Hildering

Dive buddy Natasha Dickinson with Thetys salp. ©2015 Jackie Hildering

I was pretty sure that it was the solitary form of some species of salp but  . . . so big?

Pelagic tunicate. Salp species - Thetys, solitary phase. To 33 cm. ©2015 Jackie Hildering

Good view of gut. ©2015 Jackie Hildering

As soon as I got home I grabbed my copy of Wrobel and Mills’ “Pelagic Coast Pelagic Invertebrates” and emailed a few photos of this unique find to Andy Lamb, co-author of Marine Life of the Pacific Northwest.

Ahh – it’s wonderful to have friends in deep places. Andy came back very quickly with the ID. It was a salp indeed, in fact, the world’s biggest. Thetys* in the solitary form can grow to 33 cm!

From Dave Wrobel’s The JelliesZone webpage: “Thetys is truly an impressive member of the zooplankton.  It is the largest species of salp along the West Coast and is relatively easy to distinguish from all others.  Unlike most gelatinous animals, the body is relatively firm due to the thick spiny test (the test, or tunic, is the hard outer covering typical of many tunicates, hence the name for the group).  It retains its shape even when removed from the water.  Solitary individuals have 20 partial muscle bands . . . that are used for constricting the body while pumping water for feeding and locomotion.  A pair of pigmented posterior projections are very distinctive, as is the darkly colored, compact gut . . . Like other salps, Thetys continuous pumps water through a mucous net to extract phytoplankton and other small particles.   Although relatively uncommon in Monterey Bay [and therefore very uncommon so much further north where I sighted this individual], this widespread species can be found in temperate and tropical waters of the Pacific, Atlantic and Indian Oceans, to depths of about 150 meters.”

Pelagic tunicate. Salp species - Thetys, solitary phase. To 33 cm. ©2015 Jackie Hildering

©2015 Jackie Hildering

I was intrigued how an animal that lives in the open Ocean and depends on plankton could be so big?

How could it filter enough plankton out of the water?

Pelagic tunicate. Salp species - Thetys, solitary phase. To 33 cm. ©2015 Jackie Hildering

©2015 Jackie Hildering

I came upon research from MIT (2010) that revealed how salps could get enough nutrients to be so big and fast growing.  Their mucus nets are astounding in how they are able to trap incredibly small-sized plankton. With this find, the researchers referenced salps as “the vacuum cleaners of the ocean” and confirmed how important they are because of what they do to huge volumes of climate-changing carbon.

In the Oceanus Magazine article Salps Catch the Ocean’s Tiniest Organisms, the researchers explain “As they eat, they [the salps] consume a very broad range of carbon-containing particles and efficiently pack the carbon into large, dense fecal pellets that sink rapidly to the ocean depths, Madin said. “This removes carbon from the surface waters,” Sutherland said, “and brings it to a depth where you won’t see it again for years to centuries.” And more carbon sinking to the bottom reduces the amount and concentration of carbon in the upper ocean, letting more carbon dioxide enter the ocean from the atmosphere, explained Stocker” [thereby reducing the amount in the atmosphere where it impacts climate.]

I of course also hoped to find a good photo or video of the salp chain of this species (the aggregate form) and came upon this 1-minute clip by Patrick Anders Webster (taken off the coast of central California).

Wow!!! Mind-blown again.

 

And below, an additional video from Patrick from May 2016, also off the coast of California.

 

[*You may have noticed that the full scientific name for this tunicate species is Thetys vagina as assigned by the German naturalist Wilhelm Gottlieb Tilesius von Tilenau in 1802. Likely at that time, “vagina” did not yet have its anatomical meaning and the species name was chosen for the Latin origin of the word meaning “wrapper” / “sheath”.]

 

Further information:

Scripps zooplankton guide – https://scripps.ucsd.edu/zooplanktonguide/species/thetys-vagina

Jelly Zone – http://jellieszone.com/pelagic-tunicates/thetys/