PUBLISHED November 11, 2010

A Portuguese man-of-war is actually a colony of individual organisms called polyps. Photograph by Mike Theiss, Nat Geo Image Collection

Common Name: Portuguese Man-of-War Scientific Name: Physalia physalis Type: Invertebrates Diet: Carnivore Size: Float: 12 inches long: 5 inches wide; tentacles: up to 165 feet long Size relative to a 6-ft man IUCN Red List Status: close The IUCN Red List of Threatened Species is widely recognized as the most comprehensive, objective global approach for evaluating the conservation status of plant and animal species. lc Least Concern At relatively low risk of extinction nt Near Threatened Likely to become vulnerable in the near future vu Vulnerable At high risk of extinction in the wild en Endangered At very high risk of extinction in the wild cr Critically Endangered At extremely high risk of extinction in the wild ew Extinct in the Wild Survives only in captivity ex Extinct No surviving individuals in the wild or in captivity Data Deficient Not enough information available to make an assessment Not Evaluated No assessment has been made ? Not Evaluated lc nt vu en cr ew ex least concern extinct Current Population Trend: Unknown

Anyone unfamiliar with the biology of the venomous Portuguese man-of-war would likely mistake it for a jellyfish. Not only is it not a jellyfish, it's not even an "it," but a "they." The Portuguese man-of-war is a siphonophore, an animal made up of a colony of organisms working together.

Colony Structure, Tentacles, and Venom

The man-of-war comprises four separate polyps. It gets its name from the uppermost polyp, a gas-filled bladder, or pneumatophore, which sits above the water and somewhat resembles an old warship at full sail. Man-of-wars are also known as bluebottles for the purple-blue color of their pneumatophores.

The tentacles are the man-of-war's second organism. These long, thin tendrils can extend 165 feet in length below the surface, although 30 feet is more the average. They are covered in venom-filled nematocysts used to paralyze and kill fish and other small creatures. For humans, a man-of-war sting is excruciatingly painful, but rarely deadly. But beware—even dead man-of-wars washed up on shore can deliver a sting.

Muscles in the tentacles draw prey up to a polyp containing the gastrozooids or digestive organisms. A fourth polyp contains the reproductive organisms.

Movement

Man-of-wars are found, sometimes in groups of 1,000 or more, floating in warm waters throughout the world's oceans. They have no independent means of propulsion and either drift on the currents or catch the wind with their pneumatophores. To avoid threats on the surface, they can deflate their air bags and briefly submerge.

WATCH: Stunning Video of the Portuguese Man-of-War Up Close The Portuguese man-of-war—a colonial organism related to the jellyfish—is infamous for its painful sting, but one photographer finds the beauty inside this animal's dangerous embrace.