The typical jellyfish found in Majorca are not really good swimmers and they usually arrive to the beach by the sea currents. They feed from small fish after injecting them with paralysing poison. For people, the sting of one of these jellyfish is just painful.
In the Mediterranean Jellyfish do not attack, but if you touch their tentacles, they will sting as a defence mechanism. Usually jellyfish stings in Majorca are not critical, unless the person is allergic to the poison or has some specific disease. Even when they are not critical, they can be really painful and sore.
The typical symptoms are pain, burning and itching sensation, swelling and redness of the area and even bleeding.