Pediatric emergency medicine trisk 1994 1994

FIGURE 90.15 Marine invertebrate causing human sting.

Class Hydrozoa
Feathered hydroid (Pennaria tiarella ) is found from Maine to Florida and along
the Texas coast just below the low-tide line. They attach to solid objects,
including pilings and floats. They cause a mild sting that may be treated with
local care.
Portuguese man-of-war (Physalia physalis ) is a hydrozoan colony, although it
is commonly erroneously considered a jellyfish. The float can be up to 30 cm in
length, with tentacles hanging from the float that may reach more than 75 ft in
length and contain about 750,000 nematocysts each. This open-sea animal is
often driven ashore by storms along the Atlantic coast.
Tentacles on the skin should be fairly easy to recognize as the cause of
symptoms. Releasing one of the most powerful marine toxins, the nematocysts of