Roy S. Houston, Ph.D.
Now that summer is here, strange creatures will be arriving in our local waters. Magnificent blue jellyfish (sea jellies is more appropriate since they are not fish!) and blue buttons have already been sited along some of the South Campos beaches. These beautiful creatures are members of the Phylum Cnidaria which include the sea anemones, corals, hydroids, sea fans and a host of other animals. Cnidarians are carnivorous animals that possess tentacles containing stinging cells called cnidocytes. These specialized cells eject small harpoon-like structures known as nematocysts which are toxic and are used to paralyze their prey. Nematocysts are also used for defense against intruders, including us! In addition, cnidarians can be in the form of a polyp, like that found in sea anemones, or a medusa, which is typical of sea jellies. Polyps are sessile or not motile and can be solitary or in colonies; whereas medusa are motile and free-swimming. Many cnidarians have both body forms especially during their reproductive cycle. As our waters warm up it is not uncommon to observe increasing numbers of these magnificent creatures. In late summer blue buttons and blue jellies are joined by the Pacific man-o-wars. The striking thing is that all three critters are quite colorful with bodies of various shades of blue.
Blue cannonball jelly, aguamar, Stomopholus meleagris mainly occurs in the coastal waters of the Gulf of Mexico, Caribbean and the warm Atlantic. However, this critter ventures to the Pacific Ocean and occasionally shows up in our neck of the water. The striking feature of this species and others in the same family is they possess a thick, rigid bell (the umbrella part) without marginal tentacles. Most jellies have soft gelatinous bodies with marginal tentacles. In addition, there are 8 oral arms that are fused and hang just below the bell margin. The bell of most cannonball jellies is pale blue becoming yellow or brown towards the margin. However, some are bright blue such as in the individuals sited locally. These jellies are active swimmers and often occur in swarms and feed on small zooplankton. Cannonball jellies will produce a mild sting if handled. Treatment for all cnidarians stings is to carefully remove the tentacles with tweezers and pour vinegar over the infected area. Cannonball jellies have been harvested and can be eaten after soaked in salt and alum.
Blue Buttons, botónes, Porpita pacifica are floating hydroid colonies that are blown ashore during summer storms. Initially these creatures may be mistaken for small sea jellies or small pieces of blue plastic. The entire colony is kept afloat by a circular, blue disk which provides the needed buoyancy. The edge of the disk is fringed with polyps armed with knobby, stinging tentacles which protect the animal. Underneath the central disk hangs the feeding polyp that functions as a mouth for the colony. In between this and the tentacles are reproductive polyps that produce the gametes. Unlike the Portuguese man-o-war blue buttons do not have a powerful sting.
Pacific Man-o-war, Agua mala, Physalia utriculus is related to the infamous "Portuguese man-of-war" found in the Western Atlantic and, like it, can produce an extremely painful, nasty sting. Fortunately this animal is absent from Baja coastal waters except during late summer when individuals are carried by currents from the South and occasionally wash up on shore. These cnidarians, although they appear as single animals, are actually colonies made up of hundreds of tiny bright blue polyps. Some of these polyps produce the gas bag that enables the entire colony to stay afloat. Other polyps have tentacles up to several feet long that contain nematocysts which are used for paralyzing their prey. If you see these animals it is wise not to enter the water. The Mexicans refer to this condition as "agua mala". Pacific man-of-wars occur throughout the Eastern tropical Pacific waters.
Sea jellies and their kin are most beautiful and fascinating creatures and except for the man-o-wars, our local species produce only mild stings. However, it is always prudent to be careful when handling these creatures; even those which have wash up on beaches, for their nematocysts are still activated after the animal has died. You may not feel any sting on your hands, yet you may have a reaction if you rub your eyes, wrists or other sensitive areas. Also some individuals have developed severe allergic reactions upon repeated contact with jellies. Therefore, you should always wear gloves or some other protective wear when handling gelatinous animals. No hugging recommended!