# Spotted jelly

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 papua is one of the numerous marine animals living in symbiosis with zooxanthellae, a photosynthetic alga.

## Taxonomy

Five subspecies have been described, inhabiting separate marine lakes in the Palau 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. Unlike many other jellies, spotted jellyfish have numerous mouths along the bottom of their oral arms.
There are eight rhopalia, 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 Palau, 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

* ↑ Collins, A.G.; Morandini, A.C. (2023). World List of Scyphozoa. Mastigias papua (Lesson, 1830). Accessed through WoRMS on 2023-05-29.
* 1 2 "Spotted jelly". Monterey Bay Aquarium. Retrieved 2018-02-25.
* ↑ Dawson, Michael N (2005). "Five new subspecies of Mastigias (Scyphozoa: Rhizostomeae: Mastigiidae) from marine lakes, Palau, Micronesia" (PDF). Journal of the Marine Biological Association of the United Kingdom. 85 (3): 679–694. Bibcode:2005JMBUK..85..679D. doi:10.1017/S0025315405011604. S2CID 13572718. Archived from the original (PDF) on 2006-09-05.
* ↑ Chang, Yachun. "Mastigias papua (Golden medusa)". Animal Diversity Web. Retrieved 2024-02-29.
* 1 2 3 4 Smithsonian Environmental Research Center. "Mastigias sp. 1". invasions.si.edu. Retrieved 2024-02-29.
* ↑ Vega de Luna, Félix; Dang, Kieu-Van; Cardol, Mila; Roberty, Stéphane; Cardol, Pierre (2019-10-01). "Photosynthetic capacity of the endosymbiotic dinoflagellate Cladocopium sp. is preserved during digestion of its jellyfish host Mastigias papua by the anemone Entacmaea medusivora". FEMS Microbiology Ecology. 95 (10). doi:10.1093/femsec/fiz141. ISSN 0168-6496. PMC 6757112. PMID 31504450.
* ↑ Chang, Yachun. "Mastigias papua (Golden medusa)". Animal Diversity Web. Retrieved 2024-02-29.
* 1 2 3 Team, How It Works (2016-06-14). "Jellyfish Lake: Why is the Ongeim'l Tketau lake full of jellyfish?". How It Works. Retrieved 2024-02-29.
* ↑ Souza, Mariana Rocha De; Dawson, Michael N (2018-08-10). "Redescription of Mastigias papua (Scyphozoa, Rhizostomeae) with designation of a neotype and recognition of two additional species". Zootaxa. 4457 (4): 520–536. doi:10.11646/zootaxa.4457.4.2. ISSN 1175-5334. PMID 30314144. S2CID 52976771.
* ↑ M. Bayha and M. Graham, Keith and William (2011). "First confirmed reports of the rhizostome jellyfish Mastigias (Cnidaria: Rhizostomeae) in the Atlantic basin" (PDF). Aquatic Invasions. 6 (3): 361–366. doi:10.3391/ai.2011.6.3.13 – via REABIC.
* ↑ Fautin, D. G.; Fitt, W. K. (June 1991). "A jellyfish-eating sea anemone (Cnidaria, Actiniaria) from Palau: Entacmaea medusivora sp. nov". Hydrobiologia. 216–217 (1): 453–461. doi:10.1007/BF00026499. ISSN 0018-8158. S2CID 21758147.