Jellyfishes / Abubon Papapgo'
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Jellyfishes / Abubon Papapgo'
Dangerous Marine Life
Jellyfishes are primitive life forms that lack any form of skeleton or hard body parts. They are members of the Phylum Coelenterata (Cnidaria) which also contains the corals and sea anemones. Coelenterates have specialized stinging cells called nematocysts which are venom-filled sacs that contain a tightly coiled hollow stinging thread. When stimulated, the stinging thread uncoils through a door at the opposite end of the cell. The venom is discharged through the everted thread and is used to immobilize small fishes and other creatures that are captured for food and for defense. Prey is either drawn up into a digestive cavity in the "bell" of the jellyfish, or into a dense mass of tentacles where it is digested.
There are many kinds of jellyfishes in Guam's waters. Most are not dangerous and cause only mild stinging or itching. Some are unable to affect humans because their stinging cells are not strong enough to penetrate the skin. But a few can cause severe stings that may require immediate medical attention, and could be potentially fatal, although there have not yet been any fatalities recorded on Guam. The most dangerous jellyfishes are the sea wasps and man-'o-war. The pelagic sea wasp occasionally occurs in large concentrations in Tumon Bay when onshore winds prevail. It is clear and nearly invisible. The smaller inshore sea wasp remains hidden in the reef during the day, but emerges into the water at night. It is common in the southern bays. The man-'o-war floats on the surface and trails several blue tentacles behind it. Large concentrations are occasionally blown inshore when winds change direction.
If someone is stung by a jellyfish, the pieces of tentacles that are stuck to the skin should be carefully removed immediately by the fingers (this is all right to do since the skin of your finger is probably too tough to be stung) or by pouring alcohol on them. Do not rub sand on the wound. If symptoms worsen, seek medical attention.
Above: Inshore sea wasp Carybdea rastoni
Left: Pelagic sea wasp Carybdea alalata
Right: Indo-Pacific man-o-war Physalia utriculus
Photos © Robert F. Myers
Guam Comprehensive Wildlife Conservation Strategy, 9/27/2005
