Portuguese man o' war
The Portuguese man o' war, also known as the man-of-war, blue bottle, or floating terror is a Marine biology hydrozoan found in the Atlantic, Indian and Pacific Oceans. It is one of two species in the genus Physalia, along with the Pacific man o' war, Physalia utriculus. Physalia is the only genus in the family Physaliidae. Long tentacles have numerous venomous microscopic nematocysts which deliver a painful sting powerful enough to kill fish and even occasionally humans. Despite its appearance, the Portuguese man o' war differs from most animals called jellyfish, which are single organisms. The Portuguese man o' war is classified as a siphonophore, a colonial organism made up of many specialized, though genetically distinct, parts called zooids. These zooids are attached to one another and are physiologically integrated to such an extent that they cannot survive independently. The assemblage of zooids works together to function as an individual animal. Zooids should not be confused with zooplankton.
Etymology
The name "man o' war" comes from the man-of-war, an 18th-century sailing warship, and the cnidarian's resemblance to the Portuguese version at full sail.The names for the animal in Hawaiian include , palalia, and others.
In Australia, South Africa, and New Zealand, they are also referred to as Blue Bottles.
Habitat
The Atlantic Indian Portuguese man o' war lives at the surface of the ocean. The gas-filled bladder, or pneumatophore, remains at the surface, while the remainder is submerged. Portuguese man o' war have no means of propulsion, and move passively, driven by the winds, currents, and tides.Strong winds may drive them into bays or onto beaches. Often, finding a single Portuguese man o' war is followed by finding many others in the vicinity. Because they can sting while beached, the discovery of a man o' war washed up on a beach may lead to the closure of the beach.
Structure
Being a colonial siphonophore, the Portuguese man o' war is composed of three types of medusoids and four types of polypoids, grouped into cormidia beneath the pneumatophore, a sail-shaped structure filled with gas. The pneumatophore develops from the planula, unlike the other polyps. This sail is bilaterally symmetrical, with the tentacles at one end. It is translucent, and is tinged blue, purple, pink, or mauve. It may be long and may extend as much as above the water. The Portuguese man o' war fills its gas bladder with up to 14% carbon monoxide. The remainder is nitrogen, oxygen, and argon—atmospheric gases that diffuse into the gas bladder. Carbon dioxide also occurs at trace levels. The sail is equipped with a siphon. In the event of a surface attack, the sail can be deflated, allowing the colony to temporarily submerge.The three polyp types are known as dactylozooid, gonozooid, and gastrozooid. These polyps are clustered. The dactylozooids make up the tentacles that are typically in length, but can reach over. The long tentacles "fish" continuously through the water, and each tentacle bears stinging, venom-filled nematocysts, which sting, paralyze, and kill adult or larval squids and fishes. Large groups of Portuguese man o' war, sometimes over 1,000 individuals, may deplete fisheries. Contractile cells in each tentacle drag the prey into range of the digestive polyps, the gastrozooids, which surround and digest the food by secreting enzymes that break down proteins, carbohydrates, and fats, while the gonozooids are responsible for reproduction.
Venom
This species is responsible for up to 10,000 human stings in Australia each summer, particularly on the east coast, with some others occurring off the coast of South Australia and Western Australia.The stinging, venom-filled nematocysts in the tentacles of the Portuguese man o' war can paralyze small fish and other prey. Detached tentacles and dead specimens can sting just as painfully as the live organism in the water and may remain potent for hours or even days after the death of the organism or the detachment of the tentacle.
Stings usually cause severe pain to humans, leaving whip-like, red welts on the skin that normally last two or three days after the initial sting, though the pain should subside after about 1 to 3 hours. However, the venom can travel to the lymph nodes and may cause symptoms that mimic an allergic reaction including swelling of the larynx, airway blockage, cardiac distress, and an inability to breathe. Other symptoms can include fever and shock, and in some extreme cases, even death, although this is extremely rare. Medical attention for those exposed to large numbers of tentacles may become necessary to relieve pain or open airways if the pain becomes excruciating or lasts for more than three hours, or breathing becomes difficult. Instances where the stings completely surround the trunk of a young child are among those that have the potential to be fatal.
Treatment of stings
Stings from a Portuguese man o' war are often extremely painful. They result in severe dermatitis characterized by long, thin, open wounds that resemble those caused by a whip. These are not caused by any impact or cutting action, but by irritating urticariogenic substances in the tentacles. Salt water should not be used as a treatment.Acetic acid or a solution of ammonia and water is believed to deactivate the remaining nematocysts and usually provides some pain relief, though some isolated studies suggest that in some individuals vinegar dousing may increase toxin delivery and worsen symptoms. Vinegar has also been claimed to provoke hemorrhaging when used on the less severe stings of cnidocytes of smaller species. The current recommended treatment from studies in Australia is to avoid the use of vinegar, as local studies have shown this to exacerbate the symptoms.
The vinegar or ammonia soak is then often followed by the application of shaving cream to the wound for 30 seconds, followed by shaving the area with a razor and rinsing the razor thoroughly between each stroke. This removes any remaining unfired nematocysts. Heat in the form of hot salt water or hot packs may be applied: heat speeds the breakdown of the toxins already in the skin. Hydrocortisone cream may also be used.
Predators and prey
The Portuguese man o' war is a carnivore. Using its venomous tentacles, a man o' war traps and paralyzes its prey while "reeling" it inwards to the digestive polyps. It typically feeds on small marine organisms, such as fish and plankton., Colombia
The organism has few predators of its own; one example is the loggerhead turtle, which feeds on the Portuguese man o' war as a common part of its diet. The turtle's skin, including that of its tongue and throat, is too thick for the stings to penetrate.
The blue sea slug Glaucus atlanticus specializes in feeding on the Portuguese man o' war, as does the violet snail Janthina janthina.
The blanket octopus is immune to the venom of the Portuguese man o' war; young individuals carry broken man o' war tentacles, presumably for offensive and/or defensive purposes.
The ocean sunfish's diet, once thought to consist mainly of jellyfish, has been found to include many species, the Portuguese man o' war being one-such example.
Commensalism and symbiosis
A small fish, Nomeus gronovii, is partially immune to the venom from the stinging cells and can live among the tentacles. It seems to avoid the larger, stinging tentacles but feeds on the smaller tentacles beneath the gas bladder. The Portuguese man o' war is often found with a variety of other marine fish, including yellow jack.All these fish benefit from the shelter from predators provided by the stinging tentacles, and for the Portuguese, the presence of these species may attract other fish to eat.