200 Portuguese Men o' War sighted near Campo Beaches

Experts from the Junta's Department of the Environment reported yesterday that an analysis carried out last week came up with sightings of a total of more than 200 Portuguese Men 'o War (physalia physalis) in waters off all the beaches in the Campo de Gibraltar. The report also says that these are isolated incidents due to storms coming in from the West (i.e. the Atlantic) in February and March. They have been found in differing numbers on beaches from Sotogrande to Tarifa and beyond to Barbate and Caños de Meca, for instance. It is as well to know what to do if stung by one of these attractive-looking species:>
What is it? (Source National Geographic)

Anyone unfamiliar with the biology of the venomous Portuguese man-of-war would likely mistake it for a jellyfish. Not only is it not a jellyfish, it's not even an "it," but a "they." The Portuguese man-of-war is a siphonophore, an animal made up of a colony of organisms working together.
The man-of-war comprises four separate polyps. It gets its name from the uppermost polyp, a gas-filled bladder, or pneumatophore, which sits above the water and somewhat resembles an old warship at full sail. Man-of-wars are also known as bluebottles for the purple-blue color of their pneumatophores.
The tentacles are the man-of-war's second organism. These long, thin tendrils can extend 165 feet (50 meters) in length below the surface, although 30 feet (10 meters) is more the average. They are covered in venom-filled nematocysts used to paralyze and kill fish and other small creatures. For humans, a man-of-war sting is excruciatingly painful, but rarely deadly. But beware—even dead man-of-wars washed up on shore can deliver a sting.
Muscles in the tentacles draw prey up to a polyp containing the gastrozooids or digestive organisms. A fourth polyp contains the reproductive organisms.
Man-of-wars are found, sometimes in groups of 1,000 or more, floating in warm waters throughout the world's oceans. They have no independent means of propulsion and either drift on the currents or catch the wind with their pneumatophores. To avoid threats on the surface, they can deflate their air bags and briefly submerge.

How to treat a jellyfish sting? (Source: chemistry.about.com) 

Act quickly and calmly to remove the tentacles, stop the stinging, and deactivate any toxin.
Here is where people get confused, because the best steps to take depend on what type of animal caused the sting. Here's a good basic strategy, especially if you don't know what caused the sting:

1. Get out of the water. It's easier to deal with the sting and it takes drowning out of the equation.
2. Rinse the affected area with sea water. Do not use fresh water! Fresh water will cause any stinging cells that haven't fired (called nematocysts) to do so and release their venom, possibly worsening the situation. Do not rub sand on the area (same reason).
3. If you see any tentacles, carefully lift them off the skin and remove them with a stick, shell, credit card, or towel (just not your bare hand). They will stick to swimwear, so use caution touching clothing.
4. Keep an eye on the victim. If you see any signs of an allergic reaction, call 911 immediately. Symptoms could include difficulty breathing, nausea, or dizziness. Some redness and swelling is normal, but if it spreads outward from the sting or if you see hives on other parts of the body, that could indicate an allergic response. If you suspect a reaction, do not hesitate to seek medical attention!
5. Now... if you are sure the sting is from a jellyfish and not a Portuguese Man of War (shown below, the Man of War is not a true jellyfish) or any other animal, you can use chemistry to your advantage to inactivate the toxin, which is a protein. (Technically the venom tends to be a mixture of polypeptides and proteins including catecholamines, histamine, hyaluronidase, fibrolysins, kinins, phospholipases, and assorted toxins). How do you inactivate proteins? You can change the temperature or acidity by applying heat or an acid or base, such as vinegar or baking soda or diluted ammonia, or even an enzyme, such as the papain found in papaya and meat tenderizer. However, chemicals may cause the stinging cells to fire, which is bad news for someone allergic to jellyfish toxin or anyone stung by a Portuguese Man of War. If you do not know what caused the sting or if you suspect it is from a Man of War, do not apply fresh water or any chemical. Your best course of action is to apply heat to the affected area, since it penetrates the skin and inactivates the toxin without causing more venom to be injected. Also, heat quickly helps alleviate the pain of the sting. Hot seawater is great, but if you don't have that handy, use any warmed object.
6. Some people carry aloe vera gel, Benadryl cream, or hydrocortisone cream. I'm not sure how effective the aloe is, but Benadryl is an antihistamine, which may help limit an allergic response to the sting. Hydrocortisone can help reduce inflammation. If you seek medical attention and used Benadryl or hydrocortisone, be sure to alert the medical professionals. Acetaminophen, aspirin, or ibuprofen commonly are used to relieve pain.