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Portuguese Man O’ War And Current Displacement

Portuguese Man o'War seen by Cape May Whale Watch and Research Center

Portuguese Man o’War seen by Cape May Whale Watch and Research Center

The Portuguese Man o’ War is one of the most infamous jelly fish in the world. People who may know only the most simplistic facts about the ocean will be able to tell you that it is one of the most deadly jelly fish in the world. Lucky for us this creature is usually found in the open oceans of tropical areas, but being pushed by wind and waves have been found among various shores. Due to this summers strong gulf stream and north easterly winds, many east coast beaches, specifically northern ones, have found themselves under attack by drifting groups of these marine creatures. NBC news first reported sightings of the jellyfish washed up on an Ocean county beach on July 4th (1), with ABC news doing an additional report later the same day (2). Many people soon themselves being warned about something that they hardly even knew about.

Each Man o’ War is actually composed of several colonies of smaller individuals called zooids, which band together as they could not survive on their own. The first zooid comprises the sail and gas filled air sac which keep the organism afloat and is colored a mix of blue, purple and pink hue. This sail is can extend up to 6 inches out of the water, and is what coined this marine organisms name, due to its similar look to Portuguese warships with the same name. Several other zooids that serve functions from defense, to feeding, to reproduction, can be found in the mass below the sail, including the large streams of tentacles. These tentacles, which can reach lengths of 160 feet, are covered in stingers that troll the water for smaller marine life such as fish or shrimp. Once an organism comes in contact with the net of tentacles, the stingers deliver venom which paralyzes its prey, and allows it to be moved up the tentacle mass to the digestive polyp grouping (3).

Although these amazing creatures are found all over the globe, populations concentrate in the warmer waters below the 40 degree latitude mark, but can be carried in different directions due to a variety of factors such as stronger currents, or a more active gulf stream. These variables would cause an upwardly push of warm water, and subsequently any marine organisms that tend to favor warmer climates, up along the North Eastern shores of the United States. Looking at thermal satellite images of Florida’s coastal waters online revealed a 2 week surge in temperatures resulting in widespread scale peaks of 83 degree Fahrenheit beginning on June 13th and ending on July 30 (4). Going by the Gulf Stream’s average speed of 5.6 miles per hour (5), those warm waters would have made the 1,117.2 mile journey along the coast to New Jersey beaches in approximately 8 and a half days. This rate of speed would have moved warm tropical waters and creatures along the coast on to beaches such as the one in New Jersey, all the way up to those in New England well within the allotted time range.


By: John Rao, Intern at Cape May Whale Watch and Research Center