Yesterday our guests saw something very unusual... something so unusual that our Marine Biologist had not seen it in the two years that he has worked in the Maldives; a Pyrosome.
Difficult to bump into, bizarre, huge and "glow in the dark"; these are some words to describe a Pyrosome. One scientist even joked that they are the unicorns of the sea as they are so mysterious. So what are they?
Pyrosome does not look like a unicorn, rather like a giant, hollow sausage,
with a large opening at one end.
Drifting at the mercy of currents it is a
pelagic (open ocean), filter feeding, colony of sea squirts (tunicates).
The walls of the sausage are bumpy, as they are composed of thousands of
sea squirts which are all physically connected.
Each sea squirt sucks the water
in, in order to filter feed, and blows the water out into the hollow cavity
inside the pyrosome. The overall process of this filter feeding and pumping of
the water into the pyrosome sausage, creates an outflow of water at the open
end of the sausage; a steady jet propulsion system, which allows the animal to
move to a certain extent.
|A pyrosome... (credit to Frauke Bagusche)|
|The hollow opening..(credit to Frauke Bagusche)|
|Hundreds of tiny filter-feeding sea squirts make up a pyrosome... (credit to Frauke Bagusche)|
|(credit to Frauke Bagusche)|
The name "pyrosome" derives from the Greek words pyros meaning 'fire' and soma meaning 'body'. Why fire? Well it’s because at night, if disturbed, the pyrosome emits blue-green bioluminescence (glows in the dark)...
"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" (T.H. Huxley, 1849)
They should be on your bucket list if you love science!
P.S. Big thanks to marine biologist Frauke Bagusche, who has shared her pictures with us.