DIVE DRY WITH DR. BILL #737: FIRE BODIES
Recently I've had a lot of questions from divers and some boaters about strange pink or white cylinders that have been seen in our waters. Often the answer I give leaves the person asking it even more confused! I usually tell them it is one of your closest relatives... can't you see the family resemblance? So far no fist has marred my handsome face.
These tubular thingies are indeed more closely related to Homo sapiens than other invertebrates. No, they don't have a backbone... but their larvae do have a spinal chord and therefore are placed in the phylum Chordata. I'm talking about the fire salp, known scientifically as Pyrosoma atlanticum. The genus name Pyrosoma means fire body.
Most of the fire salps I've filmed recently have been about a foot in length and an inch in diameter. I am told they can reach up to three feet in length. The cylinder is often pink in color, but may also be white or translucent. At night they may bioluminesce, giving off a fairly bright blue green light. The origin of this light may come from tiny bacteria in the tissues of the salp. When one pyrosome flashes, others often follow suit... triggered by the light sensed from their neighbors.
The fire salp isn't an individual organism, but actually a colony of thousands of small individuals known as zooids. They are held together by the gelatinous "tunic." Despite their texture they are not related to sea jellies and do not sting.
Each individual zooid has an oral siphon with cilia that force water into it. The current they create transports yummy plankton into a mucus net they secrete. The zooids are located on the outside of the cylinder. The current moves through them into the open cylinder. It is exhausted through the open posterior end of the colony. This also gives the pyrosome a limited degree of movement as it drifts with the plankton.
Although most pyrosomes are found in warmer waters, this species is one of the few that actually visits our waters. Some of the other species frequent the warm upper layers of the water column, and some may be found at great depths. Some species may undertake daily vertical migrations of about half a mile. By doing so they transport carbon (in the form of their plankton food and their bodies) from the photosynthetic upper layers of the ocean down to the dark depths where their excretion and death releases carbon for deep water life.
I've observed several of these mass die-offs over my nearly 50 years of diving Catalina. Recent ones included a dive with Jason Manix down at Moonstone Beach back in 2010 and while filming mating squid with Jean-Michel Cousteau in 2013. I have not seen any convincing explanation for the mass mortality that precedes these events. Given their relatively high carbon content, it seems that several of our local fish including the garibaldi like to nip at them.
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Pyrosoma atlanticum colonies showing pink coloration and garibaldi chowing down on them.
Recently I've had a lot of questions from divers and some boaters about strange pink or white cylinders that have been seen in our waters. Often the answer I give leaves the person asking it even more confused! I usually tell them it is one of your closest relatives... can't you see the family resemblance? So far no fist has marred my handsome face.
These tubular thingies are indeed more closely related to Homo sapiens than other invertebrates. No, they don't have a backbone... but their larvae do have a spinal chord and therefore are placed in the phylum Chordata. I'm talking about the fire salp, known scientifically as Pyrosoma atlanticum. The genus name Pyrosoma means fire body.
Most of the fire salps I've filmed recently have been about a foot in length and an inch in diameter. I am told they can reach up to three feet in length. The cylinder is often pink in color, but may also be white or translucent. At night they may bioluminesce, giving off a fairly bright blue green light. The origin of this light may come from tiny bacteria in the tissues of the salp. When one pyrosome flashes, others often follow suit... triggered by the light sensed from their neighbors.
The fire salp isn't an individual organism, but actually a colony of thousands of small individuals known as zooids. They are held together by the gelatinous "tunic." Despite their texture they are not related to sea jellies and do not sting.
Each individual zooid has an oral siphon with cilia that force water into it. The current they create transports yummy plankton into a mucus net they secrete. The zooids are located on the outside of the cylinder. The current moves through them into the open cylinder. It is exhausted through the open posterior end of the colony. This also gives the pyrosome a limited degree of movement as it drifts with the plankton.
Although most pyrosomes are found in warmer waters, this species is one of the few that actually visits our waters. Some of the other species frequent the warm upper layers of the water column, and some may be found at great depths. Some species may undertake daily vertical migrations of about half a mile. By doing so they transport carbon (in the form of their plankton food and their bodies) from the photosynthetic upper layers of the ocean down to the dark depths where their excretion and death releases carbon for deep water life.
I've observed several of these mass die-offs over my nearly 50 years of diving Catalina. Recent ones included a dive with Jason Manix down at Moonstone Beach back in 2010 and while filming mating squid with Jean-Michel Cousteau in 2013. I have not seen any convincing explanation for the mass mortality that precedes these events. Given their relatively high carbon content, it seems that several of our local fish including the garibaldi like to nip at them.
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Pyrosoma atlanticum colonies showing pink coloration and garibaldi chowing down on them.
