Danger - no swimming!
VulcanSpirit
Richard & Alison Brunstrom
Sun 29 May 2011 22:29
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The seas around Bermuda are full of poisonous
Portuguese men o'war, Physalia physalia. They look a bit like jellyfish
to the uninitiated but actually they are a colonial hydroid (related more
closely to sea anemones and corals). There are four specialist types of animal
in the colony. One makes the pneumatophore, a bladder up to 300mm long filled
with gas (mostly carbon dioxide), which enables the colony to float along the
surface of the sea and be blown by the wind. Under the bladder are stinging
tentacles often 10m long and sometimes many times longer which sweep the surface
waters for its planktonic prey. The stinging cells have a tightly coiled harpoon
and can inject a strong poison which will inflict an extremely painful
sting to human skin lasting for a couple of days - a few human fatalities have
even been recorded. These animals are occasionally washed up on the beaches of
the UK - don't touch them because the tentacles can still sting even several
days after the colony has died on the beach. But if you very gently (so as
not to hurt it) touch a common red strawberry anemone in a rock pool with
your finger you will feel that it is 'sticky'. In fact what you are feeling is
the stinging cells' harpoons which are not strong enough to hurt humans - but it
is exactly the same mechanism.
Anyway here is one sailing/drifting along,
photographed from the boat as we approached Bermuda
 In this shot you can see the top of the tentacles
at the right hand side. Remember that the nearly invisible tentacles are
probably 10m and more long, and there are thousands and thousands of these at
sea. They make a tasty meal for turtles whose skin is too tough to get stung -
shame we've hunted them nearly to extinction.
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