Physalia

Abstract: Jellyfish tentacles in contact with human skin can produce pain swelling and redness. The pain is due to discharge of jellyfish nematocysts and associated toxins and discharge can be caused by a variety of mechanical and chemical stimuli. A series of tests were carried out with chemicals traditionally used to treat jellyfish stings e.g. acetic acid ammonia meat tenderizer baking soda and urea to determine if these chemicals stimulated or inhibited nematocyst discharge and if they brought relief to testers who were exposed to jellyfish tentacles. Chrysaora quinquecirrha (sea nettle) Chiropsalmus quadrumanus (sea wasp) and Physalia physalis (Portuguese man-of-war) were used in the study. It was found that many of the chemicals traditionally used to treat jellyfish stings stimulated nematocyst discharge and did not relieve the pain. However there was immediate relief when a common anesthetic lidocaine was sprayed on the skin of testers in contact with jellyfish tentacles. Initial exposure of tentacle suspensions to lidocaine prevented the nematocyst discharge by subsequent exposure to acetic acid ethanol ammonia or bromelain. Thus lidocaine in addition to acting as an anesthetic on skin in contact with jellyfish tentacles inhibited nematocyst discharge possibly by blocking sodium and/or calcium channels of the nematocytes.

Abstract: The general composition and conditions of reactivity of the nematocysts and nematocyst contents of Physalia are described. A method is presented for isolation of nematocysts without contamination by other tentacular material. The nematocyst content appears to be a highly labile protein complex. The toxicity of the capsule contents is destroyed or denatured by heating to 60° C., by drying, by treatment with ethyl ether, acetone, or ethanol. Activity may be preserved for two months when the material is stored at - 5° C. The approximate lethal dose for mice, when the toxin was injected intraperitoneally, was 0.037 ml./kilo. of a preparation, which contained 0.201% total N. The toxin was shown to be devoid of hemolytic activity for fish erythrocytes. When tested in fish, frogs or mice it appeared to affect the nervous system, particularly the respiratory centers, before voluntary muscles. Localized changes in cardiovascular tone have been observed in some test animals. Physalia toxin elicited responses in the...

Abstract: The nematocysts of 24 siphonophore species were examined by light and scanning electron microscopy (SEM) for differences that could relate to differences in the sizes and types of prey captured. The siphonophore species in the suborder Calycophorae had 4-30 microbasic mastigophores (0.7-18.0 µl volume), and 50-2000 smaller homotrichous anisorhizas in uncoiled nematocyst batteries. The physonect siphonophore species had 4-120 stenoteles or microbasic mastigophores (1.8-40.7 µl volume), and 150-20,500 smaller homotrichous anisorhizas in coiled nematocyst batteries. The sizes of crustacean prey (primarily copepods) captured by species in both suborders increased with increasing nematocyst size and numbers. Examination by SEM of captured, but uningested prey showed that the heavily-spined threads of these nematocysts adhered to the prey surface, and primarily entangled the prey. In contrast, the tentacles of siphonophores in the suborder Cystonectae, which includes Physalia physalis, have only isorhizas of 1....

Abstract: In 2010, the Mediterranean basin experienced Portuguese Man-of-War (Physalia physalis) swarms that had dramatic consequences, including the region’s first recorded human fatality attributed to a jellyfish sting. Despite the impact of jellyfish on coastal economic activity and the importance of the tourism industry for the Mediterranean region (accounting for 15% of global tourism), no scientific consensus has been achieved regarding the causes of this episode. Here, we analyse the meteorological and oceanographic conditions of the North-East Atlantic Ocean during the months previous to the appearance of P. physalis in the Mediterranean. We simulate the probable drift of Atlantic populations into the Mediterranean basin with a numerical model and compare model results with available observations. We conclude that the summer 2010 P. Physalis swarm was the result of an unusual combination of meteorological and oceanographic conditions during the previous winter and not a permanent invasion favoured by climatic changes.