The Portuguese man-of-war is a floating hydrozoan. It is actually a colony consisting of four types of polyps: a pneumatophore, or float; dactylozooids, or tentacles; gastrozooids, or feeding zooids; and gonozooids which produce gametes for reproduction. Cnidocytes (stinging cells) are located in the tentacles. Their action is based on their individual osmotic and hydrostatic pressure. Sensory cells are numerous and are located in the epidermis of the tentacles and the region around the mouths. Generally, the sensory cells are receptors for touch and temperature.
The stinging cells, or cnidocytes, are the characteristic food-getting mechanisms of jellyfish and their close relatives. P. physalis has two sizes of cnidocytes, some small and others are large. These cells retain their potency long after an individual has been washed up along the shore, as many hikers along beaches have discovered to their dismay and discomfort.
Other Physical Features: ectothermic ; heterothermic ; venomous