Integrated within this group we find jellyfish, anemones, corals, etc.

The well-known jellyfish, popularly known in Cuba as "Aguas Malas" (Bad Waters) are simple organisms with several types of radial symmetry, composed of a transparent jelly-like substance that forms their general constitution. A characteristic that they share is the presence of nematocistes (arrow cells), specialized structures for defense and for capturing fish.

Some of these species are more toxic than others, this is especially true of the "Portuguese Man-of War" (Physalia physalis) which has a mostly blue color, and which comes to our coasts mainly at the end of the winter or at the onset of weather changes.

Another species is the "Dedalillo" (Linuche unguiculata), an organism in the form of a cap or thimble, which is about 2 centimeters long and has a deep red pigmentation. They move by constant pulsating movements. Sometimes they appear in extensive groups near the surface of the water, which at a distance looks like a big patch of brownish cream.

Man is injured by direct contact with these species, because then they discharge their arrow cells releasing toxins. The clinical symptoms usually are: skin affections; local pain; itch and various others that vary according to several factors.

If this happens, we should leave the water as soon as possible; do not rub sand on the skin and do not wash with fresh water, but go to the nearest health care center to will receive medical treatment.

As a prevention measure it is important not to swim in areas where the massive presence of jellyfish has been reported and not to swim after atmospheric storms; use an isothermic suit for diving if possible.