Creature Feature: Portuguese Man O'War

Biusch/CC-BY-SA-3.0, via Wikimedia Commons

Bruce Moravchik/NOAA

Along with most other sea creatures, we think Portuguese Men O'War (Physalia physalis) are really cool. However, please do not touch or approach them if you see one in the water or on the beach. They can have long tentacles and pack a nasty sting--Christian, our director of Field Research, once got a little piece of tentacle on his toes and it's about the grumpiest we've ever seen him. 

Although people often think that Portuguese Men O'War are jellyfish, they're actually something called siphonophores--instead of being one organism made up of individual cells,  it is a colony made up of tiny specialized individuals called zooids, all working together. The gas filled float at the surface, called a pneumatophore, can be pink, purple, blue or some combination. Tentacles are normally 30 feet long or less, however, individuals have been recorded with much longer (165 ft) tentacles, so it's a good idea to give a Man O'War a wide berth. Even individuals that have been washed up on the beach for a few days may still be able to sting. 

• They're called Portuguese Men O'War because they supposedly look like historic Portuguese warships in full sail. They're also sometimes called bluebottles.
• They do not propel themselves, but rely on tides, currents and winds to move them through the open ocean. Men O'War are left or right "handed"--their pneumatophore leans to one side or the other. This means that individuals in the same winds won't necessarily go in the same direction. 
• They eat fish, shrimp, and crustaceans--basically whatever small creatures the zooids which make up the tentacles (called dactylozooids) come across. 
• Loggerhead Sea Turtles love to eat Portuguese Men O'War. Their skin is too thick for the dactylzooids to penetrate!
• The Blanket Octopus, which is immune to Man O'War venom, will rip their tentacles off and carry them around to use as a weapon  in hunting or defense.