Carybdea morandinii
| Carybdea morandinii | ||||||||||||
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| Scientific name | ||||||||||||
| Carybdea morandinii | ||||||||||||
| Straehler-Pohl & Jarms , 2011 |
Carybdea morandinii is a type of box jellyfish (Cubozoa) from the family of the Carybdeidae . The species was discovered in a salt water basin in the tropical aquarium in Hagenbeck's zoo in Hamburg . The natural habitat of the species is believed to be in East Asia. Very unusual for box jellyfish, both the polyp and medusa contain zooxanthellae . The specific epithet honors the cnidarians specialist André Carrara Morandini .
features
The fully developed Cubopoly lives solitary . The elongated, up to about 1.8 mm body is divided into three parts, a dome-shaped to balloon-shaped hypostome region , an amphora-shaped calyx region and a stalk region. The gastric space is divided by a diaphragm into an oral cavity and a calyx cavity. The foot disk is enclosed by a thin peridermal collar. The hypostome is surrounded by a single ring of up to 16 tentacles (9 to 16, mean: 13, n = 30). Zooxanthellae are embedded in the tissue in the tentacles, the hypostome around the mouth opening and in the upper calyx region . The nettle cells are stenotles and hterotrich microbasic euryteles.
The straight detached medusae are tetra radially symmetrical with a hemispherical-pyramidal Umbrella (average height: 0.70 mm, average length: 0.5 mm). The outside of the umbrella has very small (0.03 to 0.04 mm) round, irregularly distributed warts covered with stinging cells. The nettle cells are mainly ovate, heterotrichic microbasic eurytelae and a few round holotric isorhizas. The manubrium is four-lipped and takes up about 30% of the screen height. The lips of the manubrium, the velarium and the nettle cell clusters on the exumbrella also contain zooxanthellae. There are five gastric filaments .
The medusa has four thread-like tentacles that are longer than the height of the umbrella when fully extended. They are white with thin, light brown annuli. The stinging cells of the tentacles belong to the following types: holotric isorhizas, atrichic isorhizas, and individual ovoid heterotrichi microbasic eurytelae.
Way of life and reproduction
So far, the way of life could only be examined under laboratory conditions. In addition, it has not yet been possible to breed the medusas to sexual maturity. Cubopolypen and young jellyfish were once a day with Artemia - nauplii fed.
Under unfavorable conditions such as water temperatures below 15 ° C or higher than 27 ° C, the polyps develop persistence stages. The polyps contracted into balls and were encased in a transparent layer of mucus. The mucous layer hardens and is attached to the substrate by means of slime threads. If the threads of mucus were cut, they were either formed again in calm water and the cyst reattached to the subsurface, or the cyst drifted away when the water was moving and new threads of mucus were formed on the surface of the water. When the favorable temperatures for the polyps were restored in the water, the polyps crept out of the cyst envelope and regenerated within a week to a fully formed cubopoly.
Asexual reproduction
So far it has not been possible to breed the medusas to sexual maturity. Therefore, no information on sexual reproduction is possible so far.
In asexual reproduction in the polyp stage, two types of reproduction were observed: Type 1 crawling cubopolypes by budding and type 2 longitudinal division of a cubopolypes.
Type 1: Creeping cubopolypes. Under favorable living conditions and when the polyps were well nourished and fully developed (minimum size 1 mm, 12 tentacles), one, rarely two, buds formed in the calyx region at the same time. Depending on the nutritional status and size of the parent polyp, the buds were 0.3 to 3 mm in length (mean: 2 mm, n = 30). The pinched-off buds were worm-like with a pointed posterior end that had clusters of stenotles in the mesogloea and a truncated anterior end with a small hypostome surrounded by 4 to 8 tentacles. The tips of the tentacles did not yet contain stinging cells, but these were kept at the base of the tentacles. The creeping polyps crawled around for two to three days before they settled. The creeping polyps transformed into fixed polyps. At temperatures higher than 25 ° the creeping phase lasted 7 to 10 days. Even fully developed polyps transformed into creeping polyps. The creeping phase lasted until the temperature fell below 25 ° C again.
After metamorphosis of older polyps into a medusa, some of the younger polyps began to reproduce asexually by longitudinal division. The process began with the enlargement of the dome-like hypostome. Longitudinal furrows formed on the sides, the basal foot disk divided into two disks. The two foot disks now moved further and further apart and the division progressed from bottom to top until the two daughter polyps were only connected to one another in the mouth region. Ultimately, this contact also broke. Often the two daughter polyps that developed were not the same size. Longitudinal division could be observed several times in one polyp.
metamorphosis
The onset of metamorphosis of the Cubopoly could not be triggered by changing the water temperature or by adding potassium iodide . In the laboratory, the metamorphosis only took place from May to September, when the room temperature in the laboratory rose to around 25 ° C and had at least 5 hours of direct sunlight. Mass production of creeping polyps was observed approximately four weeks prior to the onset of metamorphosis. The first sign of the incipient metamorphosis was the flattening of the hypostome and the formation of four furrows; the hypostome briefly assumed the shape of a four-leaf clover. The stem elongated and became transparent. The tentacle bases fused, became bud-like, and the free ends were resorbed. Before the resorption of the tentacles was complete, pigment spots formed on the regressed tentacle bases on the side facing the hypostome. These pigment spots developed into the rhopalia. On the side of the buds facing away from the hypostome, the statocysts formed somewhat later. Later, a horizontal furrow appeared in the calyx region and divided the calyx region into a metamorphosing, medusoid upper part and a polyp-like lower part. The upper part then lost its radial symmetry and turned into a cube-like shape. The hypostome expanded like a balloon. After the conversion of the tentacle bases into the Rhopalia was completed, the tentacles of the future Medusa formed between the Rhopalia. While the tentacles grew to their full length, the constriction between the upper part of the calyx and the lower part of the calyx slowly moved down the stem. A deep transverse furrow formed around the inflated hypostome and initiated remodeling of the hypostome into the manubrium. The screen formed, and many nettle cell stains appeared on the exumbrella. After the transformation of the hypostome into the manubrium was completed, the screen began to pulsate and the stem was absorbed. The young medusa peeled off after the stem was completely absorbed. Occasionally the basal disk could still be seen at the apex of the umbrella of the detached medusa, but it receded and completely disappeared within the first two days. The metamorphosis of a cubopoly into a medusa took a total of about three to seven days and was always complete, i. H. without leaving a regenerative residue.
literature
- Ilka Straehler-Pohl and Gerhard Jarms: Morphology and life cycle of Carybdea morandinii, sp. nov. (Cnidaria), a cubozoan with zooxanthellae and peculiar polyp anatomy. Zootaxa, 2755: 36-56, 2011.