DIVE DRY WITH DR. BILL #760: THE GIANT PYROSOME
One blustery weekend in March, I drove down to the dive park to see if any of my friends were submerging. I was pleased to see a number of them, and hear that conditions were actually pretty good "down under" (and I don't mean Australia). The kelp was healthy, visibility was decent and there were plenty of critters for folks to enjoy. Heck, I even saw a few bikinis suggesting spring is actually here!
That night I wandered in to karaoke and ended up sitting with a group of divers from the SCUBA Center in Temecula. As is often the case when I encounter divers, Martyn Draper asked if I could identify a critter he and his wife Thamar had imaged in the dive park. I hadn't brought my glasses so I borrowed his and saw what appeared to be a pyrosome or fire salp. I asked how large it was and was astounded when he said at least 20 feet. The pyrosomes we usually encounter here, Pyrosoma atlanticum, rarely reach two feet in length.
Martyn said that one diver had checked the Internet and thought it was a "sea pickle." I had not heard that common name before so I Googled it and discovered that was another name for a pyrosome! I'd always called the ones we see here occasionally fire salps or French ticklers (if you get my drift), except when talking to fellow marine biologists. In that case I'd use their scientific name.
Indeed there are pyrosomes that may reach incredible lengths of 60 feet or more, so I felt this sighting was of a different species altogether, perhaps Pyrosoma spinosum. One source listed it as Pyrostremma spinosum so there may have been a name change... those taxonomists like to keep us on our toes! In all my nearly 50 years of diving here, I had never encountered one like this. A reliable source indicated that this species is circumtropical and is also found in temperate oceans like the waters here off Catalina.
Pyrosomes are invertebrates but their larvae possess a primitive central nerve chord which places them in the same phylum as humans, the Chordata. I don't really see any family resemblance, but they are our closest invertebrate relatives! Technically they are colonies of individuals or zoids that function together. The shape of the colony is tubular (surfers should like that) and they feed by drawing sea water in from outside the colony, filtering yummy plankton out of it and expelling the water through the hollow end of the tube. This also serves as the colony's propulsion system.
They are known as fire salps because of their bioluminescence. Each zoid has two light organs at its outer end that produce light. It is thought that the light may actually be produced by bacteria held captive in the light organs. When one zoid emits light, adjacent ones are often triggered as well, creating a wave or pulse of light along the colony's tube. The light they generate is in the blue-green end of the spectrum.
Further research by yours truly uncovered the fact that the giant pyrosome, Pyrosoma spinosum, was first noted by the scientific expedition on the vessel H.M.S."Challenger" which sailed between 1873 and 1876. Back in my Harvard daze, I would occasionally visit the Museum of Comparative Zoology. In its incredible library I was able to actually hold an ancient copy of the Challenger expedition reports... a real piece of oceanographic history.
As I Googled on, I was intrigued by one source that suggested our massive troop build up during the Vietnam conflict may have been "triggered" by the giant pyrosome! Those of us who were around back in the 1960s (and, gulp, even two decades earlier) may remember the Tonkin Gulf incident that President Johnson used to escalate our involvement. As reported back then, the USS Maddox was spying on Vietnamese radar installations on several offshore islands. It was reportedly attacked by three Vietnamese vessels, but escaped.
It later returned along with the USS Turner Joy to continue its intelligence gathering effort. A storm hit that night and crew on the two vessels reported seeing torpedoes and bright lines that suggested another attack by the Vietnamese. The Maddox and Turner Joy defended themselves using evasive maneuvers, cannon and depth charges. However, after the "battle," no Vietnamese vessels were detected! The captain of the Maddox sent a message indicating he was skeptical about the "attack." However, Secretary of Defense McNamara recommended air strikes against North Vietnam and President Johnson was given full war powers by Congress.
When previously classified documents about this incident were declassified, it was learned that President Johnson's response was “For all I know, our navy was shooting at whales out there.” A marine biologist on hearing about the skeptical reports suggested that the "torpedoes" and bright lights observed may have come from colonies of the giant pyrosome! Sad to believe our involvement there may have deepened and tens of thousands of our brave military personnel killed due to mistaken identity.
© 2018 Dr. Bill Bushing. For the entire archived set of over 750 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: The more commonly seen fire salp in our waters, Pyrosoma atlanticum (top) and the giant pyrosome imaged in our dive park (courtesy of Martyn and Thamar Draper).
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One blustery weekend in March, I drove down to the dive park to see if any of my friends were submerging. I was pleased to see a number of them, and hear that conditions were actually pretty good "down under" (and I don't mean Australia). The kelp was healthy, visibility was decent and there were plenty of critters for folks to enjoy. Heck, I even saw a few bikinis suggesting spring is actually here!
That night I wandered in to karaoke and ended up sitting with a group of divers from the SCUBA Center in Temecula. As is often the case when I encounter divers, Martyn Draper asked if I could identify a critter he and his wife Thamar had imaged in the dive park. I hadn't brought my glasses so I borrowed his and saw what appeared to be a pyrosome or fire salp. I asked how large it was and was astounded when he said at least 20 feet. The pyrosomes we usually encounter here, Pyrosoma atlanticum, rarely reach two feet in length.
Martyn said that one diver had checked the Internet and thought it was a "sea pickle." I had not heard that common name before so I Googled it and discovered that was another name for a pyrosome! I'd always called the ones we see here occasionally fire salps or French ticklers (if you get my drift), except when talking to fellow marine biologists. In that case I'd use their scientific name.
Indeed there are pyrosomes that may reach incredible lengths of 60 feet or more, so I felt this sighting was of a different species altogether, perhaps Pyrosoma spinosum. One source listed it as Pyrostremma spinosum so there may have been a name change... those taxonomists like to keep us on our toes! In all my nearly 50 years of diving here, I had never encountered one like this. A reliable source indicated that this species is circumtropical and is also found in temperate oceans like the waters here off Catalina.
Pyrosomes are invertebrates but their larvae possess a primitive central nerve chord which places them in the same phylum as humans, the Chordata. I don't really see any family resemblance, but they are our closest invertebrate relatives! Technically they are colonies of individuals or zoids that function together. The shape of the colony is tubular (surfers should like that) and they feed by drawing sea water in from outside the colony, filtering yummy plankton out of it and expelling the water through the hollow end of the tube. This also serves as the colony's propulsion system.
They are known as fire salps because of their bioluminescence. Each zoid has two light organs at its outer end that produce light. It is thought that the light may actually be produced by bacteria held captive in the light organs. When one zoid emits light, adjacent ones are often triggered as well, creating a wave or pulse of light along the colony's tube. The light they generate is in the blue-green end of the spectrum.
Further research by yours truly uncovered the fact that the giant pyrosome, Pyrosoma spinosum, was first noted by the scientific expedition on the vessel H.M.S."Challenger" which sailed between 1873 and 1876. Back in my Harvard daze, I would occasionally visit the Museum of Comparative Zoology. In its incredible library I was able to actually hold an ancient copy of the Challenger expedition reports... a real piece of oceanographic history.
As I Googled on, I was intrigued by one source that suggested our massive troop build up during the Vietnam conflict may have been "triggered" by the giant pyrosome! Those of us who were around back in the 1960s (and, gulp, even two decades earlier) may remember the Tonkin Gulf incident that President Johnson used to escalate our involvement. As reported back then, the USS Maddox was spying on Vietnamese radar installations on several offshore islands. It was reportedly attacked by three Vietnamese vessels, but escaped.
It later returned along with the USS Turner Joy to continue its intelligence gathering effort. A storm hit that night and crew on the two vessels reported seeing torpedoes and bright lines that suggested another attack by the Vietnamese. The Maddox and Turner Joy defended themselves using evasive maneuvers, cannon and depth charges. However, after the "battle," no Vietnamese vessels were detected! The captain of the Maddox sent a message indicating he was skeptical about the "attack." However, Secretary of Defense McNamara recommended air strikes against North Vietnam and President Johnson was given full war powers by Congress.
When previously classified documents about this incident were declassified, it was learned that President Johnson's response was “For all I know, our navy was shooting at whales out there.” A marine biologist on hearing about the skeptical reports suggested that the "torpedoes" and bright lights observed may have come from colonies of the giant pyrosome! Sad to believe our involvement there may have deepened and tens of thousands of our brave military personnel killed due to mistaken identity.
© 2018 Dr. Bill Bushing. For the entire archived set of over 750 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: The more commonly seen fire salp in our waters, Pyrosoma atlanticum (top) and the giant pyrosome imaged in our dive park (courtesy of Martyn and Thamar Draper).
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