Portuguese Man o War or Box Jelly – Which Is It?

HONOLULU, Hawaii. January 7. "STINGS from Portuguese man o war tend to be erratic in shape," explains marine expert Dr. Gail Grabowsky of Honolulu, Hawaii.

"The man o war tentacles stick to the skin. Then, the swimmers touches them or gets further entangled and they end up with some really zig-zag scars."

The box jellyfish have very straight tentacles and, in contrast to the Portuguese man o war, their stings often leave a linear sting. Additionally, there is often that sort of purple line in the skin at the center of the tentacle. Most importantly, if a swimmers is stung at night [during their swims], that is very telling. Man o war are at the surface day and night.

The cubomedusae – or box jellies – have the most complex eyes of all jellyfish. They sense light and dark very well and some people think their eyes may even be able to partially form images. They may actually use their eyes to hunt. But we know they use them to sense daylight and most species – including the Carybdea species in Hawaii (shown above) – are highly negatively phototactic. That is, they avoid light and go deep during the day, only to the surface at night.

These species live in the waters between Cuba and Florida where Diana Nyad was swimming last year. They are native to Puerto Rico and probably much of the waters nearby.

The box jellyfish in Hawaii have behavioral patterns that coincide with the states of the moon so you are much more likely to get stung on certain nights. The jellies converge in bays and near shore on these nights. No one really knows where they are on the other nights; we presume somewhere out at sea. Or in the depths."

The question to ask is how far offshore from land was the swimmer when they were stung?

"Swimmers can be stung by a number of different species including the mauve jellyfish/stinger which are very painful, but these are not box jellies. So other kinds of jellyfish can be to blame," continued Dr. Grabowsky. "Swimmers need to find out just what pelagic species of jellies roam the sea where they are swimming and which ones surface at night."

Four tentacles, many tentacles. Awfully agonizing or caustically painful? Anyway you look at these stings, there are a huge barrier to open water swimmers.

Photos of Diana Nyad's stings from the Florida Strait last year are posted here. Photos of Penny Palfrey's stings from Hawaii between Oahu and Kauai in 2011 are posted here.

Courtesy of Open Water Source

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