Portuguese man o' war
The Portuguese man o' war, also called the man-of-war, bluebottle, or floating terror, is a siphonophore that grows from 3.5-12in. It is translucent, and is tinged blue, purple, or pink. Depending on the person or how much venom a human takes in from being stung the man-of-war is essentially non lethal but it can also cause serious effects in rare cases such as, fever, shock, and interference with the heart. Detached tentacles or dead organisms can remain potent for hours or even days after they wash up on shore. The sting leaves welts that look like red veins and will disappear in 2-3 days.
The Portuguese man o' war lives at the surface of the ocean. The gas-filled bladder, remains at the surface, while the tentacles are floating underwater. Since the man-of-war has no means of self movement, it is moved by a combination of winds, currents, and tides. It is most commonly found in the open ocean in tropical and subtropical regions. Strong winds may drive them into bays or onto beaches. Most times the finding of a single man-of-war results in the finding of many others in the vicinity. The discovery of a man o' war washed up on a beach may lead to the closure of the whole beach.