User:Toysword/Spotted Jelly

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Spotted jelly

The Spotted jelly, lagoon jelly, golden medusa, or Papuan jellyfish (Mastigias papua) is a species of jellyfish from the Indo-Pacific. The Mastigias papua belongs to the Medusozoa subphylum of the phylum Cnidaria. The Mastigias papua belongs specifically to the Mastigias genus of the Mastigiidae family of the order Rhizostomeae of the class Scyphozoa belongings to the Medusozoa subphylum. The Mastigias papua has many nicknames; one such nickname, the lagoon jellyfish, is derived from the tendency of the lagoon jellyfish to habitat lagoons and bays in the Pacific Ocean.

Physical Features

The Mastigias papua, unlike other jellyfish species, do not have tentacles. Instead of tentacles they have eight mouth-arms which they use to consume zooplankton, tiny invertebrates, or zooxanthella. These mouth arms are covered in many tiny mouths that send food towards the jellyfish body. The benefit of these oral arms is that the Mastigias papua does not need to manipulate tentacles to move food into the jellyfish’s mouth as is the case with jellyfish species that lack oral arms. The bell of the Mastigias Papua is translucent, with a diameter ranging from 30 to 120 mm wide.^[1] Like other jellyfish in the Sycphozoa class, the Mastigias Papua lacks organs commonly found in other marine animals such as eyes, gills, fins, and a heart. In place of a brain the Mastigias Papua has a nervous system capable of receiving light and odors.

The Mastigias papua has varying physical features depending on where it lives. The individual jellyfish in different populations vary in size, length of arms and terminal clubs, diameter of bell, and several other features. One such difference is whether or not the particular jellyfish has detachable terminable clubs. The occurrence of detachable terminable clubs is most evident in habitats where the jellyfish has many predators, whereas the trait is not found or is vestigial in habitats where the jellyfish population has no or lacks natural predators.^[2] Certain populations of Mastigias papua found in lagoons have blue pigments in their skin while other populations of jellyfish found in meromictic marine lakes do not have the same skin color.^[2] As a species, the Mastigias papua has not been evaluated as endangered. No extensive count of their population numbers has been taken.

Behavior

Mastigias papua get most of their energy through their symbiotic relationship with the zooxanthella they consume. The jellyfish do not actually eat the zooxanthella, instead they absorb the byproducts ejected by the zooxanthella during the process of photosynthesis. Due to their reliance of zooxanthella, the Mastigias Papua follow a daily routine that benefits both the jellyfish and the zooxanthella. The Mastigias Papua swim east in the morning with the rising of the sun and west in the afternoon when the sun sets.^[3] This behavior is more apparent in lagoon jellyfish than the jellyfish found in the oceans where sunlight is not blocked by elevated land or trees. The Mastigias papua can live alone as they do not require other members of their species to stay alive, but they tend to group up when catching sunlight. During nighttime the Mastigias Papua descend to depths where there is little to no oxygen.^[3] At these depths the water contains nutrients excreted by bacteria in the water. The zooxanthella consume the nutrients until sunrise when the Mastigias papua ascends again to bathe in sunlight.

Natural Predators

The Mastigias papua population in Jellyfish Lake in Palau are preyed upon by the sea anemone Entacmaea medusivora.^[4] The Entacmaea medusivora consume the Mastigias papua by capturing them with their tentacles and expanding their gastro vascular cavity (gut) to fit the jellyfish inside.^[4] The sea anemone reside in the shallow water shaded by mangrove roots on the bottom of the lake. Due to the tendency of the spotted jelly to stay in the sun, the spotted jelly population naturally avoids the immediate vicinity of Entacmaea medusivora.

The Mastigias papua is venomous and has the ability to sting its prey or to deter predators. When pressure is applied to the oral arms the nematocysts will release a stinger under pressure that punctures the skin and injects venom. Similar to a harpoon, this stinger is attached to the jellyfish by a long hollow thread through which the venom is funneled into the victim.^[5] The Mastigias papua’s venom is not strong enough to kill a human. However, it is potent enough to cause rashes, swelling, and general discomfort.

Reproduction

Mastigias Papua can reproduce sexually or asexually by budding. The male Mastigias Papua ejects sperm that fertilizes eggs produced by the female. These fertilized eggs float independent of the parents eating food that floats by. The parent organisms do not take care of the young in any way. Mastigias Papua do not practice post-natal care. In asexual reproduction the Mastigias Papua do not need a sexual partner to reproduce. Asexual reproduction occurs when the Mastigias Papua undergoes budding. Budding produces polyps. These polyps can bud off to form more polyps. If conditions are right then these polyps can form adult Mastigias Papua. Asexual production can occur year round. A generation of sexually reproducing Mastigias Papua is followed by a generation of asexually reproducing Mastigias Papua. ^[1]

References

^{[2] [3] [1] [4] [5]}