Box jellyfish
shaped, rather than domed or crown-shaped. The underside of the umbrella
includes a flap, or velarium, concentrating and increasing the flow of
water expelled from the umbrella. As a result, box jellyfish can move more
rapidly than other jellyfish. In fact, speeds of up to six meters per minute
have been recorded.[1]
The box jellyfish's nervous system is also more developed than that of many
other jellyfish. Notably, they possess a nerve ring around the base of the
umbrella that coordinates their pulsing movements; a feature found elsewhere
only in the crown jellyfish. Where as some other jellyfish do
have simple pigment-cup ocelli, box jellyfish are unique in the
possession of true eyes, complete with retinas, corneas and lenses. Their eyes are located on each of the
four sides of their bell in clusters called rhopalia. This enables them to see
specific points of light, as opposed to simply distinguishing between light and
the dark. Box jellies also retain the lesser type of eye[clarification needed],
because the strong eyes[clarification needed] are
only one of four subsets. They therefore have 24 eyes.[2] A box
jellyfish has the closest thing a known jellyfish has to a brain. Tests have
shown that they have a limited memory, and have a limited ability to learn.
The tentacles of some species can reach up to 3 metres in length. Box
jellyfish can weigh up to 2 kg
Although the box jellyfish can been called "the world's most venomous
creature",[11] only
a few species in the class have been confirmed to be involved in human deaths,
and some species pose no serious threat at all. For example, the sting of Chiropsella bart only results in short-lived
itching and mild pain.[12]
In Australia, fatalities are most often perpetrated by the largest species of
this class of jellyfish Chironex fleckeri. In December 2012, Angel
Yanagihara of the University of Hawaii's Department of Tropical Medicine found
the venom causes cells to become porous enough to allow potassium leakage,
causing hyperkalemia which can lead to cardiovascular
collapse and death as quickly as within 2 to 5 minutes. She postulates a zinc
compound may be developed as an antidote.[13]
The recently discovered and very similar Chironex yamaguchii may be equally dangerous,
as it has been implicated in several deaths in Japan.[5] It is
unclear hence which of these species is the one usually involved in fatalities
in the Malay Archipelago.[5][14] In
1990, a 4-year-old child died after being stung by Chiropsalmus
quadrumanus at Galveston Island in the Gulf
of Mexico, and either this species or Chiropsoides buitendijki are considered the
likely perpetrators of two deaths in West
Malaysia.[14] At
least two deaths in Australia have been attributed to the thumbnail-sized Irukandji jellyfish.[15][16] Those
who fall victim to these may suffer severe physical and psychological symptoms
known as Irukandji syndrome.[17]
Nevertheless, most victims do survive, and out of 62 people treated for
Irukandji envenomation in Australia in 1996, almost half could be discharged
home with few or no symptoms after 6 hours, and only two remained hospitalized
approximately a day after they were stung.[17]
In Australia, C. fleckeri has caused at least 64 deaths since the
first report in 1883,[18] but
even in this species most encounters appear to only result in mild
envenoming.[19] Most
recent deaths in Australia have been in children, which is linked to their
smaller body mass.[18] In
parts of the Malay Archipelago, the number of lethal cases is
far higher (in the Philippines alone, an estimated 20-40 die
annually from Chirodropid stings), likely due to limited access
to medical facilities and antivenom, and the fact that many Australian
beaches are enclosed in nets and have vinegar placed in prominent positions allowing
for rapid first aid.[19][20]
Vinegar is also used as treatment by locals in the Philippines.[14]
Box jellyfish are known as the "suckerpunch" of the sea not only because
their sting is rarely detected until the venom is injected, but also because
they are almost transparent.[21]
In northern Australia, the highest risk period for the box jellyfish is
between October and May, but stings and specimens have been reported all months
of the year. Similarly, the highest risk conditions are those with calm water
and a light, onshore breeze; however, stings and specimens have been reported in
all conditions.
In Hawaii, box jellyfish numbers peak approximately
7 to 10 days after a full moon, when they come near the shore to
spawn. Sometimes the influx is so severe that lifeguards have closed infested
beaches, such as Hanauma Bay, until the numbers subside.[22][23]
[edit] Treatment of stings
Once a tentacle of the box jellyfish adheres to skin, it
pumps nematocysts with venom into the skin, causing the sting and agonizing
pain. Domestic vinegars have been confirmed as an effective treatment as they
disable the sea wasp's nematocysts not yet discharged into the bloodstream.
Pressure immobilisation can also be used on limbs to slow down the spreading of
the deadly venom. Common practice is to apply generous amounts of vinegar prior
to and after the stinging tentacle is removed.[24]
Removal of additional tentacles is usually done with a towel or gloved hand, to
prevent secondary stinging. Tentacles will still sting if separated from the
bell, or after the creature is dead. Removal of tentacles without prior
application of vinegar may cause unfired nematocysts to come into contact with
the skin and fire, resulting in a greater degree of envenomation.[citation needed]
Although commonly recommended in folklore and even some papers on sting
treatment,[25] there
is no scientific evidence that urine, ammonia, meat tenderizer, sodium bicarbonate, boric acid, lemon
juice, fresh water, steroid cream, alcohol, cold packs, papaya, or hydrogen peroxide will disable further stinging,
and these substances may even hasten the release of venom.[26]
Pressure immobilization bandages, methylated spirits, or vodka should never be
used for jelly stings.[27][28][29][30] In
severe Chironex fleckeri stings cardiac arrest can
occur quickly, so cardiopulmonary resuscitation (CPR) can be
life-saving and takes priority over all other treatment options.[citation needed]
In 2011, University of Hawaii Assistant Research Professor Angel Yanagihara
announced that she had developed an antivenom by "deconstructing" the venom
contained in the box jellyfish tentacles.[31] Its
effectiveness was demonstrated in the PBS NOVA documentary Venom: Nature's
Killer, originally shown on North American television in February 2012.[32]
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Box Jellyfish
Cubozoa
![Photo: A box jellyfish beneath the water's surface](http://images.nationalgeographic.com/wpf/media-live/photos/000/004/cache/box-jellyfish_482_600x450.jpg)
The box jellyfish's venom is among the most deadly in the world, containing toxins that attack the heart, nervous system, and skin cells.
Photograph by David Doubilet
Map
![Map: Jellyfish range](http://images.nationalgeographic.com/wpf/media-live/graphic/map-box-jellyfish-160-20007-cb1273172091.gif)
Box Jellyfish Range
Fast Facts
- Type:
- Invertebrate
- Diet:
- Carnivore
- Average life span in the wild:
- Less than 1 year
- Size:
- 10 ft (3 m) long; 10 in (25 cm) across
- Weight:
- Up to 4.4 lbs (2 kg)
- Group name:
- Fluther or smack
- Did you know?
- Sea turtles are unaffected by the sting of the box jellyfish and regularly eat them.
- Size relative to a 6-ft (2-m) man:
-
The infamous box jellyfish developed its frighteningly powerful venom to instantly stun or kill prey, like fish and shrimp, so their struggle to escape wouldn’t damage its delicate tentacles.
Their venom is considered to be among the most deadly in the world, containing toxins that attack the heart, nervous system, and skin cells. It is so overpoweringly painful, human victims have been known to go into shock and drown or die of heart failure before even reaching shore. Survivors can experience considerable pain for weeks and often have significant scarring where the tentacles made contact.
Box jellies, also called sea wasps and marine stingers, live primarily in coastal waters off Northern Australia and throughout the Indo-Pacific. They are pale blue and transparent in color and get their name from the cube-like shape of their bell. Up to 15 tentacles grow from each corner of the bell and can reach 10 feet (3 meters) in length. Each tentacle has about 5,000 stinging cells, which are triggered not by touch but by the presence of a chemical on the outer layer of its prey.
Box jellies are highly advanced among jellyfish. They have developed the ability to move rather than just drift, jetting at up to four knots through the water. They also have eyes grouped in clusters of six on the four sides of their bell. Each cluster includes a pair of eyes with a sophisticated lens, retina, iris and cornea, although without a central nervous system, scientists aren’t sure how they process what they see.
Other Stinging Animals
Invertebrate Features
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