Thursday, October 14, 2010

Portuguese Man of war

by: Noni Heers

I. Introduction

Domain: Eukaryota

Kingdom: Animalia

Phylum: Chordata

Class: Actinopterygii

Subclass: Actinopterygii

Order: Perciformes

Family: Nomeidae

Genus: Nomeus

Scientific name: - Nomeus gronovii

The Portuguese man-of-war is a type of jellyfish. Although it may appear to be just an “it”, it is actually a “they”. The man-of-war is known as a Siphonophore which means it is a colony of individual organisms working together. The man-of-war is made up of four separate polyps. Pneumatophore, Gastrozooid, Gonozooids, Neumatocysts and Dactylozooids. It gets its name, Man-of-War from the uppermost polyp,which is a gas-filled bladder, or pneumatophore, which sits above the water and somewhat resembles an old warship at full sail. Man-of-wars are also known as bluebottles for the purple-blue color of their pneumatophores. The Nematocysts are a very complex coiled and thread like intercellular structure. They are part of the Dactylozoids. Their purposes is to drag the prey into its mouth (gastrozooids). The tentacles can extend 165 feet in length below the surface, although 30 feet is more the average.

Nematocysts are covered in venom-filled nematocysts used to paralyze and kill fish and other small creatures. For humans, a man-of-war sting is extremely painful but not deadly.

The Gonozooids consist of male and female part, they can reproduce by a sexual budding or asexually. With sexually budding they achieve variation with in the species by producing gametes. With asexual reproduction they produce an exact copy of themselves. The Gastrozooid is the digestive part (feeding zooids) of the man-of-war.

The man-of-war is found in tropical Atlantic waters and occasionally as far north as the Bay of Fundy and the Hebrides and also the Mediterranean Sea. It can usually be found floating on top of the water but can quickly submerge when danger is near. They are reported abundantly off the Karachi coast in Pakistan, particularly at the Sandspit and Hawkes Bay beaches during the months of June, July and August, and are also common in the ocean off parts of Australia and New Zealand.

II. Anatomy

The Man-of-War floats on a gas-filled, blue to pink, translucent body called a pneumatophore The body is 3 to 12 inches long. The crest above the float acts like a sail, moving the animal across the seas. Polyps support the tentacles and are located under the float. On the Man-of-war, there are 4 types of polyps (explained above).

III. Form and Function

The man-of-war is constantly looking for food with its tentacles. The food that is found is trapped in the tentacles (dactylozooids) with the help their nematocysts. Nematocysts stinging barbs shoot out whenever the cells are disturbed, usually by something brushing up against them. Once it finds its prey it usually gets the fish by stinging it with its 10 to 100 foot long tentacles releasing poison into the fish's body. Once the fish becomes paralyzed the man-of-war pulls the small fish into its mouth. The man-of-war usually feeds on small fish.

There were different ways of reproduction that i found for man-of-war’s. Portuguese man-of-war have separate sexes and release their eggs and sperm into the sea, where fertilization occurs and larvae develop. The larvae bud and grow into adults that reproduce sexually. The other way was that scientists believe that man-of-wars spawn together in large numbers, with each colony (being either all male polyps or all female polyps) releasing gametes into the water to be fertilized. The result larvae then go through asexual budding to produce a new

man-of-war colony.

Just because the man-of-war is a jellyfish doesn’t mean that it doesn’t have enemies. The Sun Fish, Loggerhead Turtle, and Hawksbill Turtle all feed on the Portuguese man-of-war. it defends itself by using its nematocysts. One predator that the man-of-war can’t escape is the Glaucus which is a type of sea slug that uses the man-of-war’s tentacles for itself after it eats them.

IV. Impact on the World/ Humanity


Portuguese men-of-war can harm the tourism industry. People will not pay to visit beaches that are covered with jellyfish or swim in waters where they are floating. People do not want to chance being stung or put their children at risk for stings. Men-of-war have the potential to impact the fishing industry. Fish harvests could be influenced by man-of-war feeding on larval fish populations, especially in areas with major commercial fisheries, such as the Gulf of Mexico.


Portuguese Men-of-war do benefit the economy as well. They are eaten by some fish and crustaceans of commercial value. In addition, the man-of-war could fill an important ecological role that has not yet been studied that keeps the ecosystem in balance.

V. Journal Article Review

In this Article the person who is talking said that they were out one day by the beach when they spotted the man of war by the rocks. so this person decided to try to throw the man of war further out into the ocean so that it wouldn’t sting anybody else. The narrator also says that man of war’s are usually responsible for severe stings in Myrtle Beach. it was said that the reason they had found all of those man of wars was because of the change in wind.


Works Cited:

Hydroids: hydrozoa- portuguese man of war (physalia physalis): species accounts.” (n.d.). Retrieved from

Hoover, Initials. (n.d.). “Marine Invertebrates Of Bermuda.” Retrieved from

Portuguese man-of-war. (n.d.). Retrieved from

Lee, J.B. (n.d.). Hawaiian ocean organisms. Retrieved from

Pmow. (n.d.). Retrieved from

Spring, J. (n.d.). Jellyfish blowing in the wind. Retrieved from

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