The golden jellyfish (''Mastigias papua'' cf. ''etpisoni'') is a subspecies of spotted jellyfish (''

Mastigias papua The spotted jelly (''Mastigias papua''), lagoon jelly, golden medusa, or Papuan jellyfish, is a species of jellyfish from the Indo-Pacific oceans. Like corals, sea anemones, and other sea jellies, it belongs to the phylum Cnidaria. ''Mastigias p ...

'') that inhabits

Jellyfish Lake Jellyfish Lake ( pau, Ongeim'l Tketau, lit=Fifth Lake) is a marine lake located on Eil Malk island in Palau. Eil Malk is part of the Rock Islands, a group of small, rocky, mostly uninhabited islands in Palau's Southern Lagoon, between Koror an ...

Eil Malk Eil Malk or Mecherchar is the main island of the Mecherchar Islands, an island group of Palau in the Pacific Ocean. In a more narrow sense, just the southeastern peninsula of Mecherchar is called Eil Malk. Geography Eil Malk is located 23 kil ...

island in

Palau Palau,, officially the Republic of Palau and historically ''Belau'', ''Palaos'' or ''Pelew'', is an island country and microstate in the western Pacific. The nation has approximately 340 islands and connects the western chain of the Caro ...

in the western Pacific Ocean. Like the nominate subspecies, it derives part of its nutrition from

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 ...

algae (

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 ...

) that live in their tissues and part of their nutrition from captured

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

. The golden jellyfish is morphologically, physiologically, and behaviourally distinct from the spotted jellyfish. It was described as a separate subspecies in 2011, together with four other new subspecies inhabiting nearby marine lakes. The species identification is uncertain (denoted by

cf. The abbreviation ''cf.'' (short for the la, confer/conferatur, both meaning "compare") is used in writing to refer the reader to other material to make a comparison with the topic being discussed. Style guides recommend that ''cf.'' be used onl ...

in the name) because the individuals local to Palauan lagoons may be only one of several

cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

that make up the ''M. papua'' group. It is distinguished by the almost complete loss of spots on the exumbrella and the almost complete loss of their clubs, an appendage attached to the oral arms.

Ecology

The subspecies carries out well-characterized daily migrations that are driven by light conditions in the lake. From 1998 onwards, a steep decline in the golden jellyfish

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 ...

population was detected in Jellyfish Lake. By December 1998, the medusa population had declined to zero. This was followed by a resurgence in 2000, and the population had returned to pre-decline levels in 2012. This was apparently caused by a die-off of the symbiotic zooxanthellae due to increased water temperatures during an

El Niño El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date L ...

weather event.

References

{{Taxonbar, from=Q3298066 Mastigiidae