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card
154

Portuguese
man-of-war

OLogy Series
animal
card
154

Portuguese
man-of-war

OLogy Series
animal

The Portuguese man-of-war is actually a floating colony of individuals called polyps that are all dependent on each other for survival. One large polyp forms a gas-filled, blue, translucent body that floats above the surface. Long tentacles that dangle down in the water are specialized to detect and capture prey. Other polyps are specialized for digesting prey once it is captured.

The Portuguese man-of-war catches small fish to eat by:

strangling them with its long tentacles

swimming in circles to make them dizzy

stinging them

Are you right?

Correct!

The Portuguese man-of-war's long tentacles are armed with stinging cells called "nematocysts." Each of these cells has coils of threads that are covered with little spines or barbs. The cells shoot out this barbed thread and it sticks into the prey.

The Portuguese man-of-war travels throughout the world's warm seas by:

shooting water out of a pouch to push it through the water

using a crest or sail to float with winds and currents

swiftly pedaling its tentacles

Are you right?

Correct!

The gas-filled float has a crest that acts like a sail and helps it travel with the wind and currents. In fact, this creature was named by medieval sailors who compared it to a Portuguese sailing ship.

If you see a Portuguese man-of-war on the beach, it's probably dead and safe to touch.

Fact
or
Fiction
?

Fiction

Even when a dead man-of-war has washed up on the beach, its tentacles can still sting. So if you see one, stay clear!

The Portuguese man-of-war can float or sink if in danger.

Fact
or
Fiction
?

Fact

In stormy weather, the Portuguese man-of-war can deflate its float and sink beneath the surface, safe from wind and waves.

Portuguese man-of-war
Scientific name: Physalia physalis
Size: tentacles up to 165 feet long
Habitat: warm water environments of the Pacific and Indian oceans
Diet: algae, plankton, small crustaceans
Characteristics: gas-filled, purplish-blue float; tentacles; moves using the crest of the float
Significance: predator of a range of marine organisms; some fish and sea turtles prey on it

Image credits: courtesy of Dr. Thomas, M. Scott, Florida Geological Survey.