Portuguese Man-of-War
Don't let its appearance fool you. That blob floating in the ocean is far from innocuous and it isn't a jellyfish. As the name implies, the Portuguese Man-of-War isn't a nice beast to meet in the ocean, as roughly 10,000 people swimming off the Australian coast discover each year. The creature is actually a "colonial organism" made of multiple polyps, the largest, a bladder filled with gas that is similar to the atmosphere, is often mistaken for a jellyfish — and it gives the animal it's name since the bladder looks like the sail of an old Man-of-War battle ship). The other three polyps, gastrozooid (feeding), gonozooid (reproduction) and dactylozooid (defense), are clustered around the bladder. The dactylzooids compose tentacles that can be more than 150 feet in length. Tiny fish can live in the tentacles, but when a human or larger fish is stung, the venom leaves red welts that can last multiple days. The recommended treatment is to apply salt water to the sting. Unlike jelly fish, vinegar is not recommended as a treatment, and contrary to old wives' tales, urine is not a recommended treatment for a jellyfish or a Man-of-War. Let's just say that avoiding this animal all together is the best defense.