Mastigias papuaGolden medusa

Geographic Range

Mastigias papua is widely distributed through the Indian Ocean, China Sea to Japan, and outward over the Pacific to the Fiji Islands. Found as far west as the Indo-West Pacific, M. papua has the greatest morphological diversity in Palau. In Palau, a radiation of forms has resulted in the recognition of many subspecies of M. papua that are morphologically distinct. (Dawson, 2005; Mayer, 1910; Monterey Bay Aquarium, 2010)


The lagoon jellyfish is found in the ocean, where it tends to dwell within the top 2.5 m of the water during the day to allow its symbiotic zooxanthellae access to light. Sunlight governs its life, especially in the Palau lakes, and this species follows the sun from west to east until it reaches the shadows near the shore. When the sun is setting, the lagoon jellyfish sinks to lower levels of its habitat. Mastigias papua requires specific temperature, salinity, and exogenous cues for proper strobilation (transverse fission). They also respond evolutionarily to their specific habitats, as demonstrated by the endemic speciation of M. papua in the Palau lakes. (Dawson, 2005; Graham, et al., 2001; Hale, 1999; Mayer, 1910; Sugiura, 1963; Sugiura, 1964)

  • Average elevation
    131 m
    429.79 ft
  • Range depth
    1 (high) m
    3.28 (high) ft

Physical Description

The lagoon jellyfish has many subspecies that grow more dissimilar as they age. There are considerable morphological differences among subspecies that live in different environments, gather in different populations, and even between the individual jellyfish themselves. Four main morphological differences are used to differentiate between these subspecies: the number and shape of the velar lappets (flaps), the length of the mouth arms relative to bell radius, the length of the terminal clubs relative to bell radius, and color. The following summarizes the features that are considered characteristic of the traditional lagoon jellyfish. (Dawson, 2005; Mayer, 1910; Sasaki, et al., 2002)

The translucent bell of Mastigias papua is usually hemispherical, with a diameter ranging from 30 to 80 mm. This species has 8 frilled oral arms, rather than tentacles, whose total length is approximately equal to the bell-radius. The mouth arms are divided into two sections: a simple upper part, which tends to be about 1.5 times as long as the 3 winged lower part of the arm. These arms end in a club-like filament that has a triangular cross section, though this is absent in some species. Each oral arm has mouths on the club, as well as along the length towards the bell. (Dawson, 2005; Kramp, 1961; Mayer, 1910; Monterey Bay Aquarium, 2010; Sasaki, et al., 2002)

Significant color variation exists within Mastigias papua, though the bell is usually greenish blue to olive green with yellow, white, and/or brown oval, granular spots across the rim (over the exumbrella). This coloring can be attributed to the zooxanthallae that reside symbiotically within the lagoon jellyfish (mostly in the mesoglea). (Dawson, 2005; Mayer, 1910; Sasaki, et al., 2002)

  • Range length
    30 to 80 mm
    1.18 to 3.15 in


Eggs of Mastigias papua hatch into tiny, oval-shaped, flat planula larvae that swim around until they find a suitable substrate to settle. This process takes a few hours to a few days, during which the mouthless larvae does not feed. Once on a substrate, M. papua attaches by its anterior end and morphs into a sessile polyp. Polyps feed on prey that floats by until they grow large enough to reproduce. At this point, they can either create motile buds asexually, or go through monodisk strobilation, forming yellow-green ephyrae. Ephyrae mature into free swimming medusa with symbiotic zooxanthellae and sensory organs. (Calder, 1982; Hale, 1999; Hofmann and Crow, 2002; Uchida, 1926)


Full-fledged medusas are dioecious and can be identified by sampling a part of their reproductive tissue and observing it under a dissecting microscope. Females also have characteristic brood filaments on their oral arms and disk. Medusa males release sperm that swim to eggs either within the brood filaments of the female or inside of her. A sexual generation (medusa) alternates with an asexual generation (polyp). There are no data on mate selection. (Calder, 1982; Kramp, 1961; Raskoff, et al., 2003; Sugiura, 1963; Uchida, 1926)

Asexual reproduction by budding can occur year round, though strobilation can only occur with cooler water temperatures since water that is too warm causes the symbiotic zooxanthallae to fail. Loss of the zooxanthellae would eliminate seventy percent of the lagoon jellyfish's food source. Other than this, the only specific observation made on how Mastigias papua breeds in the wild is that ephyrae do not seem to emerge unless the sea water temperature is around 22 degrees C. Mastigias papua polyps can reproduce asexually year-round by budding off, while medusa formation via strobilation requires lower temperatures because high temperatures kill the zooxanthellae needed for medusae to survive. (Calder, 1982; Graham, et al., 2001; Hofmann and Crow, 2002; Raskoff, et al., 2003; Sugiura, 1964)

  • Breeding interval
    Mastigias papua breed once yearly.
  • Breeding season
    Breeding season is from May to June.

Mastigias papua may brood the young in their brood filaments until they hatch, whereupon the young planulae larva will swim away and find a place to attach. No other parental investment has been identified. (Hale, 1999; Hofmann and Crow, 2002; Sugiura, 1963; Sugiura, 1964)

  • Parental Investment
  • no parental involvement
  • pre-hatching/birth
    • protecting
      • female


The records of Mastigias papua being raised in captivity are slim, the most specific of which states that lagoon jellyfish can live more than three months in captivity. No records were found indicating how long they live in the wild. (Monterey Bay Aquarium, 2010; Calder, 1982)

  • Typical lifespan
    Status: captivity
    more than 3 (high) months


Mainly solitary, Mastigias papua medusae swarm towards sunlight to bathe their zooxanthallae. If not for this feature, M. papua could be a solitary species save for periods of reproduction. The sessile polyps are also solitary, although they may sometimes seem to group if they settle in similar places due to limited availability of suitable substrate. (Dawson, 2005; Uchida, 1926)

Communication and Perception

These jellyfish have a nerve net along the bell as well as marginal sensory organs that determine the contractions which propel the medusa. All Scyphozoa have receptors that detect a variety of stimuli, including light (ocelli), smell, and touch (sensory lappets) as well as a statocyst, which coordinates balance. These are found in the triangular clubs (rhopalia), which in turn also allow control of stimulation of the statocyst so that the jellyfish can adjust the direction it is swimming. (Hale, 1999; Nicol, 1960)

Food Habits

Mastigias papua primarily derives energy from the carbon fixed by its symbiotic zooxanthallae. This energy can be absorbed from these algae directly, since they dwell within the jellyfish's tissues. Thirty percent of the jellyfish's energy is obtained from collecting zooplankton, phytoplankton, tiny invertebrates, and microbes within the oral arms' mouths. Unlike other jellies, which need to collect food with their tentacles and bring them to a central mouth under the bell, Mastigias papua engulfs its food through its mouths on the oral arms and sends it to the body via canals along these arms. (Dawson, 2005; Graham, et al., 2001; Kramp, 1961; Mayer, 1910; Turner, 2006)

  • Animal Foods
  • aquatic crustaceans
  • other marine invertebrates
  • zooplankton


Mastigias papua utilizes the nematocysts that decorate its oral arms to deter predators, and to help with capturing food. When a predator (or passerby human) applies pressure, these venomous cells inject toxins. Mammals as large as a human experience many adverse effects such as rashes, severe itching, nausea, and vomiting. The only creature that has been confirmed to prey on Mastigias papua is a sea anemone, Entacmaea medusivora. (Dawson, 2005; Fautin and Fitt, 2004; Hale, 1999; Turner, 2006)

  • Known Predators
    • Entacmaea medusivora

Ecosystem Roles

Mastigias papua hosts symbiotic zooxanthallae, and large swarms of lagoon jellyfish could be detrimental to populations of zooplankton and other small prey. Small fish have lived inside the bell of M. papua for protection until the fish reach maturity. (Dawson, 2005; Monterey Bay Aquarium, 2010; Raskoff, et al., 2003; Sasaki, et al., 2002; Turner, 2006)

Mutualist Species
  • zooxanthellae

Economic Importance for Humans: Positive

Mastigias papua have been displayed in aquariums to showcase jellies. The Palau lake M. papua also serve as a large tourist attraction. The fragile existence of this species helps to demonstrate the importance of maintaining our ecosystem. (Monterey Bay Aquarium, 2010; Turner, 2006)

  • Positive Impacts
  • ecotourism
  • research and education

Economic Importance for Humans: Negative

Humans exposed to a swarm of Mastigias papua may emerge with painful rashes, nausea, and vomiting. Otherwise, there are no known adverse effects of M. papua on humans. (Dawson, 2005; Hale, 1999; Turner, 2006)

  • Negative Impacts
  • injures humans

Conservation Status

No evaluations on the conservation status of Mastigias papua have been made. However, during the 1997-98 El Niño, Palau lake water temperature and saltiness increased, causing a massive drop in jelly populations. Since hardy polyps survived the event, even though many medusa died, populations were on the rise in 2000. (Monterey Bay Aquarium, 2010; Turner, 2006)


Yachun Chang (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, Renee Mulcrone (editor), Special Projects.


Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map


reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents


an animal that mainly eats meat


uses smells or other chemicals to communicate


the nearshore aquatic habitats near a coast, or shoreline.


particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).


humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body


union of egg and spermatozoan


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


generally wanders from place to place, usually within a well-defined range.


found in the oriental region of the world. In other words, India and southeast Asia.

World Map


reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.


An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).


photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)


an animal that mainly eats plankton


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

radial symmetry

a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season


remains in the same area


non-motile; permanently attached at the base.

Attached to substratum and moving little or not at all. Synapomorphy of the Anthozoa


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).


uses sight to communicate


animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)


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Uchida, T. 1926. The anatomy and development of a Rhizostome Medusa, Mastigias papua L. Agassiz, with observations on the phylogeny of Rhizostomae. J. Faculty Sci. Imperial Univ. Tokyo Sec 4 Zool, 1: 45-95.