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Box jellyfish

2007 Schools Wikipedia Selection. Related subjects: Organisms

                           iBox Jellyfish
   "Cubomedusae", from Ernst Haeckel's Kunstformen der Natur, 1904
   "Cubomedusae", from Ernst Haeckel's Kunstformen der Natur, 1904
                      Scientific classification

   Kingdom: Animalia
   Phylum:  Cnidaria
   Class:   Cubozoa
            Werner, 1975
   Order:   Cubomedusae
            Haeckel 1877

                                  Families

   see text
   Jellyfish net enclosure at Ellis Beach, Queensland
   Enlarge
   Jellyfish net enclosure at Ellis Beach, Queensland

   Box jellyfish are water-dwelling invertebrates belonging to the class
   Cubozoa, named for their cube-shaped medusae. They share many
   characteristics with their relatives the true jellyfish in the class
   Scyphozoa. The name sea wasp is also applied to some species of
   cubozoans, including Chironex fleckeri and Carybdea alata.

   Box jellyfish are found in Australia, the Philippines, and many other
   tropical areas. They are known for the often-fatal effects of their
   venom, although not all species are venomous.

Defense and feeding mechanisms

   Box jellyfish use powerful venom contained in epidermic nematocysts to
   stun or kill their prey prior to ingestion, or as an instrument for
   defense. Their venom is among the most deadly in the animal kingdom and
   has caused at least 63 recorded deaths since 1884. Most often, these
   fatal envenomations are perpetrated by the largest species of box
   jellyfish, Chironex fleckeri, owing to its high concentration of
   nematocysts, though at least two deaths in Australia have been
   attributed to the thumbnail-sized irukandji jellyfish (Carukia
   barnesi). Those who fall victim to Carukia barnesi suffer several
   severe symptoms known as Irukandji syndrome.

   The venom of cubozoans is very distinct from that of scyphozoans, and
   is used to catch prey (fish and small invertebrates) and for defense
   from predators. Turtles, however, are unaffected by the sting and eat
   box jellyfish.

   In the Australian summer from November to April or May, box jellyfish
   are abundant in the warm waters of northern Australia and drive away
   most swimmers. It is not known where they go in the Australian winter.
   Australian researchers have used ultrasonic tagging to learn that these
   creatures sleep on the ocean floor between 3 pm and dawn. It is
   believed that they sleep to conserve energy and to avoid predators.

Vision

   Some theorize box jellyfish actively hunt their prey—for effective
   hunting they move extremely quickly (moving at speeds up to 3 to 3.5
   knots (1.5 to 1.8 m/s)) instead of drifting as do true jellyfish, and
   have an active visual system of 24 eyes located on the centre of each
   side of its bell.

   The eyes occur in clusters on the four sides of the cube-like body.
   Sixteen are simply pits of light-sensitive pigment (eight slit-shaped
   eyes and eight lens-less pit eyes), but one pair in each cluster is
   surprisingly complex, with a sophisticated lens, retina, iris and
   cornea, all in an eye only 0.1 millimeters across

   The lenses on these eyes have been analyzed and could form distortion
   free images. Despite the perfection of the lenses, the retinas of the
   eyes lie closer to the lens than the optimum focal distance, resulting
   in a blurred image. One of these eyes in each set has an iris that
   contracts in bright light. Four of the eyes can only make out simple
   light levels.

   It is not currently known how this visual information is processed by
   Cubozoa, as they lack a central nervous system, although they seem to
   have four primitive brain-like organs.

Treatment of stings

First aid

   If swimming at a beach where box jellyfish are known to be present, a
   bottle of vinegar is an extremely useful addition to the first aid kit.
   Following a sting, vinegar should be applied for a minimum of 30
   seconds. Acetic acid, found in vinegar, disables the box jellyfish's
   nematocysts that have not yet discharged into the bloodstream (though
   it will not alleviate the pain). Any adherent tentacles should then be
   removed. Removing the tentacles without first applying vinegar may
   increase discharge of nematocysts increasing envenoming. If no vinegar
   is available, however, careful removal of the tentacles by hand is
   recommended. Vinegar has helped save dozens of lives on Australian
   beaches. Although commonly recommended in folklore and even some papers
   on sting treatment, there is no scientific evidence that urine,
   ammonia, meat tenderizer, sodium bicarbonate, boric acid, lemon juice,
   or papaya will disable further stinging, and indeed these substances
   may even hasten the release of venom. Pressure immobilization bandages,
   methylated spirits, or alcohol should not be used for jellyfish stings.
   Often in severe Chironex fleckeri stings cardiac arrest occurs quickly,
   so Cardiopulmonary resuscitation (CPR) can be life saving and takes
   priority over all other treatment options (including application of
   vinegar). Activate the emergency medical system for immediate transport
   to the hospital.

Further treatment

   If the effects are minor, pain may be managed with local application of
   ice, analgesics, and antihistamines. If significant envenoming occurs,
   further treatment for systemic symptoms may be required. Box jellyfish
   (Chironex fleckeri) Antivenom is available from ambulance crews,
   hospitals, and medical centers close to where the box jellyfish are
   found. It may reduce life-threatening complications, and has been
   suggested for significant stings to possibly reduce scarring. However,
   there have been conflicting studies over the efficacy of this
   antivenom. Whether the antivenom has the potential to reverse the
   life-threatening cardiotoxicity remains uncertain. Antivenom may need
   to be given within minutes and possibly in large doses to reverse the
   symptoms of significant stings. There is no antivenom for irukandji
   (Carukia barnesi) stings with treatment being largely supportive with
   analgesia being the mainstay of management.

Prevention of stings

   Pantyhose, or tights, were once worn by Australian lifeguards to
   prevent stings. These have now been replaced by lycra stinger suits.
   Some popular recreational beaches erect enclosures (stinger nets)
   offshore to keep predators out, though smaller species such as Carukia
   barnesi can still filter through the net.

Classification

   There are two families of Cubozoa, Chirodropidae and Carybdeidae
   containing 20 species between them. A phylogenic analysis of their
   relationships is yet to be published.
     * Family Chirodropidae
          + Chironex fleckeri
          + Chirosoides buitendijkl
          + Chirodropus gorilla
          + Chirodropus palmatus
          + Chiropsalmus zygonema
          + Chiropsalmus quadrigatus
          + Chiropsalmus quadrumanus
     * Family Carybdeidae
          + Carukia barnesi
          + Manokia stiasnyi
          + Tripedalia binata
          + Tripedalia cystophora
          + Tamoya haplonema
          + Tamoya gargantua
          + Carybdea alata
          + Carybdea xaymacana
          + Carybdea sivicksi
          + Carybdea rastonii
          + Carybdea marsupialis
          + Carybdea aurifera

   Retrieved from " http://en.wikipedia.org/wiki/Box_jellyfish"
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