Hydroids: Hydrozoa - Portuguese Man Of War (physalia Physalis): Species Accounts

Physical characteristics: A Portuguese man of war colony consists of a large, purplish blue gas-filled balloon that floats on the sea surface carrying the polyps. The balloon can reach a length of almost 12 inches (30 centimeters). A sail running lengthwise along the top of the balloon allows the man of war to move with the wind. The polyps form clusters at the mouth end of the balloon. Each cluster has a reproductive polyp and a feeding-defending polyp. Each feeding-defending polyp A Portuguese man of war colony consists of a large, purplish blue gas-filled balloon that floats on the sea surface carrying the polyps. The balloon can reach a length of almost 12 inches (30 centimeters). A sail running lengthwise along the top of the balloon allows the man of war to move with the wind. (© Peter Scoones/Photo Researchers, Inc.) has a tentacle covered with extremely poisonous stingers. The tentacles can be several yards (meters) long.

Geographic range: Portuguese men of war live in the warm waters of the Pacific, Indian, and Atlantic oceans and in the Mediterranean Sea. Specific distribution map not available.

Habitat: Portuguese men of war live at the surface of the ocean. They frequently are blown ashore by strong winds.

Diet: Portuguese men of war eat plankton and small fish that they kill with their tentacles.

Behavior and reproduction: Portuguese men of war gather in large groups called navies. The sail on a man of war is either right-oriented or left-oriented, much as people are right-handed or left-handed. The wind moves "left-handed" men of war to the right and right-handed men of war to the left. Portuguese men of war have separate sexes and release their eggs and sperm into the sea, where fertilization occurs and larvae develop. The larvae bud and grow into adults that reproduce sexually.

Portuguese men of war and people: Portuguese men of war inflict very painful stings on swimmers who become tangled in their tentacles and on waders who step on them.

Conservation status: Portuguese men of war are not threatened or endangered. ∎