The spotted jelly (''Mastigias papua''), lagoon jelly, golden medusa, or Papuan jellyfish, is a species of

jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...

from the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

oceans. Like

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

s, and other sea jellies, it belongs to the

phylum In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead ...

Cnidaria Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...

. ''Mastigias papua'' is one of the numerous marine animals living in

symbiosis Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biological interaction, between two organisms of different species. The two organisms, termed symbionts, can fo ...

with

zooxanthellae Zooxanthellae (; zooxanthella) is a colloquial term for single-celled photosynthetic organisms that are able to live in symbiosis with diverse marine invertebrates including corals, jellyfish, demosponges, and nudibranchs. Most known zooxanthell ...

, a photosynthetic

alga Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...

Taxonomy

Five subspecies have been described, inhabiting separate marine lakes in the

Palau Palau, officially the Republic of Palau, is an island country in the Micronesia subregion of Oceania in the western Pacific Ocean. The Republic of Palau consists of approximately 340 islands and is the western part of the Caroline Islands ...

group. *''M.'' cf. ''p. remengesaui'' (in Uet era Ongael) *''M.'' cf. ''p. nakamurai'' (in Goby Lake) * ''M.'' cf. ''p. etpisoni'' (in Ongeim’l Tketau) *''M.'' cf. ''p. saliii'' (in Clear Lake) *''M.'' cf. ''p. remeliiki'' (in Uet era Ngermeuangel)

Description

The spotted jelly has distinctive spots atop its bell, and vary in colouration, from greenish blue to olive green, which can be attributed to the zooxanthellae which reside within their tissues. They have 8 frilled oral arms, which end in a clublike appendage. The upper surfaces of these arms are covered in stinging cells called

cnidocytes A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a ''cnidocyst'', that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ...

. Unlike many other jellies, spotted jellyfish have numerous mouths along the bottom of their oral arms. There are eight

rhopalia Rhopalia (singular: rhopalium) from Ancient Greek ῥόπαλον (''rhópalon'') 'club' are small sensory structures of certain Scyphozoan (true jellyfish) and Cubozoan (box jellyfish) species. Description The structures typically occur in mul ...

, which act as the sensory organs of the jellyfish, on the margin of the bell. They average 10cm (4 in) in diameter, but can grow as large as 30 cm (12 in).

Feeding

These jellies feed on zooplankton and other tiny organisms using their stinging cells, called cnidocytes. The spotted jelly has several small mouths used to grab animal plankton. Spotted jellies also acquire much of their nutrition via an endosymbiotic relationship with photosynthetic zooxathellae, such as those of the genus ''Cladocopium.'' The zooxathellae provide the jellyfish with nutrients, and in return the zooxanthellae get a safe place to live. This symbiotic relationship is not unique to the spotted jellyfish, and can also be observed in species such as the upside-down jellyfish. During the night, these jellyfish stay lower in the water column and migrate each day, rising to the waters surface, and following the sun east to west, to allow their zooxanthellae access to the light they need to photosynthesize.

Habitat

Spotted jellies range throughout the Indo-Pacific, from the Fijian Islands to the western Indian Ocean, and from Japan to Australia. Some populations of spotted jellies in Palau have been found to occur in huge groups (called "smacks"), which have become tourist attractions. The most famous spot to admire them is the Ongeim’l Tketau Lake in

, also known as Jellyfish Lake.

Predators

Spotted jellies are predated upon by the sea anemone '' Entacmaea medusivora,'' which capture the jellyfish in their tentacles. While the jellyfish is captured by the anemone, an enterprising gastropod or fish may scavenge upon the captured jellyfish before the anemone is finished consuming it.

Footnotes

External links

*
''Mastigias papua''
at Animal Diversity Web
''Mastigias papua''
at Monterey Bay Aquarium * {{Taxonbar, from=Q140409 Mastigiidae Articles containing video clips Animals described in 1830 Cnidarians of the Pacific Ocean Cnidarians of the Indian Ocean