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Portuguese man o’ war
– Physalia physalis –

Even though the Portuguese man o’ war looks like a single animal, appearances are deceiving. The Portuguese man o’ war is in reality a colony of animals called polyps that belong to the group known scientifically as Siphonophorae. As opposed to most known true jellyfish (in the class Scyphozoa), whose specimens are indeed a single animal, siphonophores consist of many animals. The specialised polyps form a large free-floating community (or colony), and they are connected to each other by a shared digestive system.

Portuguese man o’ wars spend most of their life on the surface. The “sail” of these animals (an air sac filled with gases) is created by specialised polyps and it floats above the surface. The remaining part of the organism, e.g. the tentacles is submerged. The animals can very probably not move on their own, and are therefore considered plankton. A combination of wind, currents and tides allows them to “sail” through the oceans. They are found in all warm regions of the world’s oceans. They most commonly occur in the tropical and subtropical regions of the Pacific and the Indian Ocean, and in the Gulf Stream in the Northern Atlantic. Strong winds at sea sometimes blow Portuguese man o’ wars into bays or out on bathing beaches.

– General information –

Further names:
German: Portugiesische Galeere

Taxonomy: Class: Hydrozoa; Order: Siphonophorae; Genus: Physalia

Appearance: The Portuguese man o’ war looks like a large bladder with very long tentacles. The large bladder, also called the “sail”, reaches a considerable length ranging from 9 to 30 cm, and a width of 10 cm. It is filled mostly with carbon monoxide and nitrogen. There are tentacles on the underside of the bladder, which can sometimes reach a length of up to 50 metres. However, they are usually not longer than 10 metres.

Feeding: The stings of the nematocysts (stinging cells) in the tentacles can paralyse small fish, crustaceans and other marine prey.

Enemies: Despite being poisonous, Portuguese man o’ wars are eaten by other animals that are immune to the venom. These include: the loggerhead sea turtle (Caretta caretta), a sea slug called the sea swallow (Glaucus atlanticus), the common purple snail (Janthina janthina) and the common blanket octopus (Tremoctopus violaceus).

Venom: Touching the tentacles causes intense pain in humans. Red welts appear on the skin, which usually only fade after 2 to 3 days. The pain subsides after about an hour. If the venom gets into the lymph nodes, the pain may be more severe. Contact with the stinging cells may also trigger an allergic reaction, which can have serious effects, such as fever, shock or rapid heartbeat. In rare cases, the stings may be lethal. Medical treatment is important, especially in cases where the severe pains persist and/or a red streak develops between a swollen lymph node and the sting, or if the affected area is red and warm to the touch.