''Cassiopea'' (upside-down jellyfish) 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 ...

true jellyfish The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish (or "true jellies"). The class name Scyphozoa comes from the Greek word ''skyphos'' (), denoting a kind of drinking cup and alluding to the ...

and the only members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow

mangrove A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...

swamps, mudflats, canals, and

turtle grass ''Thalassia testudinum'', commonly known as turtlegrass, is a species of Marine (ocean), marine seagrass. It forms meadows in shallow sandy or muddy locations in the Caribbean Sea and the Gulf of Mexico. Turtle grass and other seagrasses form sea ...

flats in

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

, and the Caribbean and

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of about 2,000 small islands in the western Pacific Ocean. It has a close shared cultural history with three other island regions: the Philippines to the west, Polynesia to the east, and ...

. The

medusa In Greek mythology, Medusa (; Ancient Greek: Μέδουσα "guardian, protectress"), also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those ...

usually lives upside-down on the bottom, which has earned them the common name. These jellyfish partake in a

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

relationship with

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s and therefore, must lie upside-down in areas with sufficient light penetration to fuel their energy source. Where found, there may be numerous individuals with varying shades of white, blue, green and brown.

Species

According to the ''

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialist ...

'', this genus includes 8 species: * ''

Cassiopea andromeda ''Cassiopea andromeda'' is one of many cnidarian species called the upside-down jellyfish. It usually lives in intertidal sand or mudflats, shallow lagoons, and around mangroves. This jellyfish, often mistaken for a sea anemone, usually keeps ...

'' (Forsskål, 1775) * ''

Cassiopea depressa ''Cassiopea'' (upside-down jellyfish) is a genus of true jellyfish and the only members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow mangrove swamps, mudflats, canals, and turtle gra ...

'' Haeckel, 1880 * ''

Cassiopea frondosa ''Cassiopea'' (upside-down jellyfish) is a genus of true jellyfish and the only members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow mangrove swamps, mudflats, canals, and turtle gra ...

'' (Pallas, 1774) * ''

Cassiopea maremetens ''Cassiopea'' (upside-down jellyfish) is a genus of true jellyfish and the only members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow mangrove swamps, mudflats, canals, and turtle gra ...

'' Gershwin, Zeidler & Davie, 2010 * ''

Cassiopea medusa ''Cassiopea'' (upside-down jellyfish) is a genus of true jellyfish and the only members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow mangrove swamps, mudflats, canals, and turtle gra ...

'' Light, 1914 * ''

Cassiopea mertensi ''Cassiopea'' (upside-down jellyfish) is a genus of true jellyfish and the only members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow mangrove swamps, mudflats, canals, and turtle gra ...

'' Brandt, 1838 * ''

Cassiopea ndrosia ''Cassiopea'' (upside-down jellyfish) is a genus of true jellyfish and the only members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow mangrove swamps, mudflats, canals, and turtle gra ...

'' Agassiz & Mayer, 1899 * ''

Cassiopea ornata ''Cassiopea ornata'' are one of many Cnidarian species called the upside-down jellyfish. This pelagic jellyfish primarily lives in tropical waters, off the coast of Australia in shallow lagoons and around mangrove trees. The name "upside-down je ...

'' Haeckel, 1880 Also recognized: * ''

Cassiopea xamachana ''Cassiopea xamachana'', commonly known as the upside-down jellyfish, is a species of jellyfish in the family Cassiopeidae. It is found in warm parts of the western Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico. It was first descr ...

'' Bigelow, 1892

Defense system

''Cassiopea'' species have a mild sting since they are primarily

, but sensitive individuals may have a stronger reaction. The photosynthesis occurs because, like most

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

s, they host

zooxanthellae Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''Sy ...

in their tissues. The stinging cells are also found in cellular masses, dubbed "cassiosomes", excreted in a

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

; people swimming near the jellyfish may come in contact with these cassiosomes and be stung. The stings, appearing in the form of a red rash-like skin irritation, are known for being extraordinarily itchy. Sometimes this jellyfish is picked up by the

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

Dorippe frascone ''Dorippe frascone'', the urchin crab or carrier crab, is a small species of crab in the family Dorippidae that was first described scientifically by J.F.W. Herbst, in 1785. It is found in the Red Sea and parts of the western and eastern Indi ...

'' and carried on its back. The crab uses the jellyfish to defend itself against possible predators.

Behavior

Certain species of ''Cassiopea'' have been observed to enter a sleep state - exhibiting decreased pulsation rate, reduced responsiveness to stimuli, and compensatory rebound sleep after deprivation.

References

External links

Photo of a Crab carrying an Upside Down Jellyfish (Cassiopea andromeda)

{{Taxonbar, from=Q289354 Cassiopeidae