''Poralia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

jellyfish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella- ...

in the family

Ulmaridae The Ulmaridae are a family of jellyfish. Genera Formerly, the genus '' Phacellophora'' was also included in this family, but is now placed in the family Phacellophoridae.Straehler-Pohl, I., C. L. Widmer, and A. C. Morandini (2011). ''Characteri ...

. It is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus containing a single species, ''Poralia rufescens''. This jellyfish is

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

, and is found in deep water in most of the world's oceans. In 2021, a

NOAA The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

expedition discovered a possible additional ''Poralia'' species in the Atlantic Ocean.

Description

''Poralia rufescens'' has a bell about in diameter. It has 30 marginal tentacles interspersed with 15 rhopalia (sensory organs). The lappets (flaps) are rectangular in outline and are all the same length, the rhopalial lappets having deep clefts and the tentacular lappets shallow clefts. This jellyfish is very fragile and most specimens examined have been damaged.

Distribution

The distribution of this meso

bathypelagic The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. The bathypelagic ...

species is not well delineated. Before 1962, only eleven damaged specimens from the North Atlantic had been examined, mostly brought up from waters deeper than . It seems to be quite common in the vicinity of Bermuda and the Bahamas, mostly in the lowest of the water column. In a study of deep sea jellyfish in the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...

performed by the USNS Eltanin, the coronates '' Periphylla periphylla'', '' Atolla wyvillei'' and '' Atolla chuni'' were the most common species found, comprising over 90% of the individuals sampled. ''P. rufescens'' was the most common semaeostome, making up 2% of the collection. A study using a

remotely operated vehicle A remotely operated underwater vehicle (technically ROUV or just ROV) is a tethered underwater mobile device, commonly called ''underwater robot''. Definition This meaning is different from remote control vehicles operating on land or in the ai ...

in deep water in the

Japan Trench The Japan Trench is an oceanic trench part of the Pacific Ring of Fire off northeast Japan. It extends from the Kuril Islands to the northern end of the Izu Islands, and is at its deepest. It links the Kuril–Kamchatka Trench to the north and t ...

showed that ''P. rufescens'' was the most common scyphomedusan there. It has also been recorded from several locations in the eastern Pacific Ocean, including off the coast of southern California.

Ecology

The biology and ecology of the mesobathypelagic jellyfishes is poorly known. Their gelatinous bodies tend to have a low proportion of protein; ''P. rufescens'' has a protein content of 0.1% of the body dry weight as compared to an average of 4% for all gelatinous taxa. Some parts of the body have a higher nitrogenous content than others, and in the Pacific,

leatherback sea turtle The leatherback sea turtle (''Dermochelys coriacea''), sometimes called the lute turtle or leathery turtle or simply the luth, is the largest of all living turtles and the heaviest non-crocodilian reptile, reaching lengths of up to and weights ...

s, whose diet consists largely of jellyfish, have been observed feeding on their

gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...

s and tentacles, the parts which have the highest nutritional values. ''Poralia'' specimens have been shown to be

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorganisms including ...

, producing blue light. The function of this is not known for this species.

References

External links

{{Taxonbar, from=Q18520932 Ulmaridae Scyphozoan genera Animals described in 1902 Monotypic cnidarian genera Bioluminescent cnidarians