''Lychnorhiza lucerna'' or Marbled Jelly is a species of jellyfish in the
order
Order, ORDER or Orders may refer to:
* A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica
* Categorization, the process in which ideas and objects are recognized, differentiated, and understood
...
Rhizostomeae
Rhizostomeae is an order of jellyfish. Species of this order have neither tentacles nor other structures at the bell's edges. Instead, they have eight highly branched oral arms, along which there are suctorial minimouth orifices. (This is in cont ...
. It is found off the Atlantic coasts of South America.
Description
When small, ''Lychnorhiza lucerna'' has a hemispherical bell, but this becomes flattened into a saucer shape as the jellyfish grows. Very large specimens have been known to reach in diameter and are dish-shaped. The upper surface is flexible and thin and is covered in low conical projections. Round the periphery are many small, triangular lappets. Hanging under the bell there are four pairs of oral tentacles, about two thirds as long as the diameter of the bell. The upper halves of these are somewhat flattened and the lower halves divide into three vanes which have multiple, inrolled edges. Among these are suctorial mouthlets leading to the interior of the bell and various thick dangling filaments. There is no central mouth. The stomach occupies most of the interior of the bell and there are a ring of small cream or white
gonad
A gonad, sex gland, or reproductive gland is a Heterocrine gland, mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gon ...
s round its edge. The colouration of this jellyfish varies, but in general, the bell is translucent and colourless or a pale shade of buff, sometimes with irregular streaks of light brown. The dangling lappets round the edge of the bell are darker brown and the lower parts of the oral tentacles may be brown as well, the upper parts being colourless.
[''Lychnorhiza lucerna'']
Marine Species Identification Portal. Retrieved 2012-04-01.
Distribution
''Lychnorhiza lucerna'' is found in tropical waters in the western Atlantic Ocean. Its range extends from French Guiana to
Buenos Aires Province
Buenos Aires, officially the Buenos Aires Province, is the largest and most populous Provinces of Argentina, Argentine province. It takes its name from the city of Buenos Aires, the capital of the country, which used to be part of the province an ...
in Argentina. It occurs in shallow coastal habitats and estuaries and is the most abundant jellyfish in its order (Rhizostomeae) in these waters. It often becomes stranded on beaches.
Life history
''Lychnorhiza lucerna'' has a complex life cycle with an alternation of sexual and asexual stages. An adult jellyfish is known as a
medusa
In Greek mythology, Medusa (; ), also called Gorgo () or the Gorgon, was one of the three Gorgons. Medusa is generally described as a woman with living snakes in place of hair; her appearance was so hideous that anyone who looked upon her wa ...
and is
gonochoristic
In biology, gonochorism is a sexual system where there are two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric.
Gonochorism contras ...
, which means that it is either male or female. The fertilized eggs hatch into
planula
A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species and also in some species of Ctenophores, which are not related to cnidarians at all. Some groups of Nemerteans also produce larva ...
larvae. These soon settle and undergo
metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...
into
sessile
Sessility, or sessile, may refer to:
* Sessility (motility), organisms which are not able to move about
* Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant
* Sessility (medicine), tumors and polyps that ...
polyps, known as a scyphistomae, with four tentacles. These grow larger, and after a series of moults have twenty-two tentacles. They develop cysts from which new polyps known as ephyrae grow. These develop transverse constrictions and separate from the original polyp by
strobilation
Strobilation or transverse fission is a form of asexual reproduction consisting of the spontaneous transverse segmentation of the body. It is observed in certain cnidarians and helminths. This mode of reproduction is characterized by high offspri ...
. The scyphistomae can strobilate several times and in a study it was estimated that one founder polyp could produce up to sixty ephyrae in a period of four months. Ephyrae develop into juvenile medusae after a further fifteen days or so.
[
]
Ecology
''Lychnorhiza lucerna'' has associations with the parasitic flatworm '' Dibothriorhynchus dinoi'', shrimps ''Periclimenes
''Periclimenes'', commonly known as glass shrimp or cleaner shrimp, is a Symbiosis, symbiotic and often Commensalism, commensalistic genus of translucent shrimp within the family Palaemonidae. Species of this large genus feature a wide variety of ...
spp'', the Atlantic bumper fish, '' Chloroscombrus chrysurus'' and the bluntnose jack, '' Hemicaranx amblyrhynchus''.[ Young spider crabs, '' Libinia ferreirae'' and '' Libinia spinosa'', use the inside of the bell as a nursery where they are safe from ]predation
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
.
References
{{Taxonbar, from=Q2139538
Lychnorhizidae
Animals described in 1880
Taxa named by Ernst Haeckel