FEATURED OKINAWAN MARINE INVERTEBRATE
Physalia utriculus

Physalia utriculus (La Martinière, 1787) rfb #3846 (bell ca. 60mm)

Featured Invertebrate Data

Taxonomy:

Frequency on Okinawa: Collection Data:
[brackets indicate range for all Okinawa-collected specimens of the species]


Species Account:

        Physalia utriculus is considered to be relatively common in Okinawan waters, although my experience has been to find them most commonly in the early months of the year (Jan~Mar).

        I don't have access to La Martinière's, 1787 description but have added the following information from EOL:

Physalia utriculus, also called Blue Bottle or (Indo-Pacific) Portuguese Man-of-War, is a marine hydrozoan of the order Siphonophora found in the Indian and Pacific oceans. A gas filled bladder allows it to float on the surface, propelled by currents, tides, and by a sail at the top of the bladder, which may be left or right-handed. A single long tentacle of venomous cnidocytes, hanging below the float, provides the animal with a means of capturing prey.
P. utriculus is distinguished from the Atlantic Portuguese Man o' War (Physalia physalis) by the smaller size of the float (six inches compared to twelve) and by having a single long fishing tentacle. Like its larger relative, P. utriculus often occurs in swarms.

Occurrence
P. utriculus is less widely distributed than the larger P. physalis, but it is the most common species on Australian coasts. It is also found in Hawaiian waters, where it is informally named ’ili mane’o or palalia.

Hazards
Individuals of P. utriculus sometimes become stranded on beaches, where their toxic nematocysts can remain potent for weeks or months in moist conditions. P. utriculus is responsible for most of the reported injuries on Australian beaches, where up to 30,000 stings are reported. Most of the incidents are on the eastern coast, with only 500 or so in western and southern waters. Unlike P. physalis, no fatalities have been recorded for P. utriculus stings.

Biology
Each individual is actually a colony of four specialized polyps and medusoids.

I've also added the following information from Wikipedia:

Physalia utriculus, also called Blue Bottle or (Indo-Pacific) Portuguese Man-of-War, is a marine hydrozoan of the order Siphonophora found in the Indian and Pacific oceans. A gas filled bladder allows it to float on the surface, propelled by currents, tides, and by a sail at the top of the bladder. A single long tentacle of venomous cnidocytes, hanging below the float, provides the animal with a means of capturing prey.

Description
Like the Atlantic Portuguese man o' war, the Indo-Pacific Portuguese man o' war is not a true jellyfish but a siphonophore, a colonial animal made up of tiny specialised animals called polyps, which are all connected to each other and function like the organs and tissues of single multicellular organisms, like fish or humans. It is composed of four separate colonies of polyps and medusoids. The colony consists of a gas-filled polyp that keeps it afloat, and three other polyp types called the gastrozooids, gonozooids and dactylozooids. Dactylozooids form tentacles that hang below the water's surface and detect and attack prey, and drag the prey up towards the gastrozooids (the digestive polyps), which attach their mouths and consume the food item. The gonozooids are adjacent to the gonozooids and constitute the reproductive structures of the colony, shedding eggs or sperm into the water.
Hazards
Individuals of P. utriculus sometimes become stranded on beaches, where their toxic nematocysts can remain potent for weeks or months in moist conditions[citation needed]. P. utriculus is responsible for most of the reported injuries on Australian beaches. On the east coast of Australia 10,000 to 30,000 stings per year from animals of the genus Physalia are reported. Most of the incidents are on the eastern coast, with only 500 or so in western and southern waters. Unlike P. physalis, no fatalities have been recorded for P. utriculus stings.

There are numerous images of Physalia utriculus found via Yahoo Search.

        I've added a second page w/ a series of images of the species.

        In addition, there's a page w/ links to misc. phyla including this species phylum, as well as additional resources.

Etymology:

Literature Cited:


Page Date: 01 Aug '17
Page Modification Date: 01 Aug '17
Digitally manipulated photo
Copyright © 2017 Robert F. Bolland