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PYROSOMA I
Pyrosoma atlanticum?
These
strange drifting creatures look gelatinous but are actually rigid
and surprisingly hard to the touch. They are not one animal but
a colony of hundreds of tiny tunicates that form a tube, closed
at one end and open at the other. The tube is covered with short,
slender, pointed projections (papillae) and if you look closely,
a tiny reddish organ is visible inside the translucent body of each
of the little tunicates. This colony was about 4-5 inches long,
though this species can apparently get much larger. The colony did
not appear to propel itself through the water, though apparently
Pyrosomas can do so as each animal takes water in along the
outer part of the tube, filters it for microscopic food particles,
and expels it into the inside of the tube, where it exits at the
open end. The genus name Pyrosoma means "fire body"
and these animals are supposed to be brightly luminescent if disturbed,
though when I handled this one I saw nothing unusual. Probably the
luminescence is visible only in the dark. An internet search turned
up something that looks very much like it called Pyrosoma atlanticum,
which is supposed to be the most common Pyrosoma in temperate
and tropical waters worldwide. Sure enough, a visit to the Bishop
Museum site shows that 2 subspecies of P. atlanticum have
been recorded from Hawaii: Pyrosoma atlanticum hawaiiensis
and Pyrosoma atlanticum paradoxum. It would probably take
an expert to determine which is which. Susan Scott wrote a fun
column on these animals. For more detailed information, check
out the neat Jellieszone
website.
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