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Jellyfish found to
release venom ‘bombs’
Words by Nicoletta LaneseU
pside-down jellyfish pulse on the
ocean floor, their frilly arms stretched
skyward as they release venom-filled
blobs of mucus into the surrounding water
where the slime ‘stings’ passing swimmers,
new research reveals.
These jellyfish (Cassiopea xamachana) look
like strange, squidgy plants stuck to the
ocean floor, and they tend to assemble in
groups that resemble bizarre flowerbeds.
Upside-down jellies can be found living in the
mangrove forests and lagoons of southern
Florida, Hawaii, the Indo-Pacific Ocean and
the Caribbean. Snorkellers who visit those
areas sometimes develop a strange itching
sensation on their skin, as if the water itself
stung them. But until now, nobody knew the
actual cause.
Researchers for the Communications
Biology journal may have finally cracked thiscase. From their spot on the seafloor, these
upside-down jellyfish deploy an arsenal of
cellular 'bombs' armed with stinging cells
called nematocytes. When these bombs make
contact with a passing swimmer they release
venom that irritates the skin. But if one of
these bomb bumps into a tiny brine shrimp
(you might know them as 'sea monkeys'), one
of the upside-down jellies’ favourite snacks,
its venom kills the animal on contact.
Those familiar with stinging water may
have heard of so-called sea lice, creatures
often blamed for the painful sensation
associated with upside-down jellies. Sea lice
are parasites that prey on fish, but the term
serves as a colloquial ‘catchall’ for anything
that causes water to sting.
None of the proposed explanations held up
to scrutiny. “We initially thought that there
would maybe be some tentacle bits from otherhttp://www.howitworksdaily.comjellyfish” floating through the water, perhaps
detached during a massive spawning event,
as can happen, said Cheryl Ames, a museum
research associate and an associate professor
of applied marine biology at Tohoku
University in Japan.
With the mystery still unsolved, the
scientists realised that whenever they were
stung, they were swimming near upside-
down jellyfish at low tide while the jellies
pumped out murky clouds of mucus. To find
out if these oddball jellies were the culprit,
the researchers looked at samples of the
jellies’ mucus under high-resolution
microscopes. They spotted tiny, jelly-filled
spheres floating within the fluid that
appeared to be packed with cells and algae.
The team uncovered one stray study from
1908 that mentioned the strange spheres, but
those researchers had wrongly identified the© Getty