Substances & Homeopatic Remedies

Medusa

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aurelia aurita

Etymology

From Greek Medousa, from feminine present participle of medein, to protect, rule over.

Family

Traditional name

Italian: Medusa
English: Sea-nettle
German: Lappenqualle

Used parts

Tincture of living animal taken in summer.

Classification

Animalia; Coelenterata / Cnidaria; Scyphozoa- Jellyfish; Semaeostoma; Ulmariidae

Keywords

Original proving

Proven by Dr. J. G. Houard.

Description of the substance

Medusa is a stage of development of the jellyfish:
Polyp = An early jellyfish life cycle (nonswimming) stage which develops into ephyra.  
Ephyra = Early free-swimming stage of jellyfish.
MEDUSA = THE ADULT FREE-SWIMMING STAGE OF THE JELLYFISH.

Description:
A flattened, transparent bell with four horseshoe shaped gonads, which are yellowish in the female and purple in the male. The margin of the bell is scalloped and divided into eight lobes. Sense organs for balance, rhopalium, are located between these marginal lobes. The radial canals of the digestive tract can also be seen near these lobes. Around the margin of the bell hang 250 short tentacles. Four elongated oral arms surround the mouth opening.
A. aurita does not have respiratory parts such as gills, lung, or trachea. Since it is a small organism, it respires by diffusing oxygen from water through the thin membrane. Within the gastrovascular cavity, low oxygenated water can be expelled and high oxygenated water can come in by ciliated action, thus increasing the diffusion of oxygen through cell (Rees, 1966). The large surface area membrane to volume helps A. aurita to diffuse more oxygen and nutrients into the cells.
The basic body plan of A. aurita consists of several parts. The species lack respiratory, excretory, and circulatory systems (Arai, 1997).  

Size:
These animals range between 5 and 40 cm.  Most are dinner plate size. Size is not an indication of age because if a moon jelly is deprived of food, it exhibits. A dinner plate sized jelly will shrink to the size of a penny until it is given food, then it will again grow to its original size.

Food:
The Saucer Jelly is carnivorous and feeds on plankton. Their primary foods include small plankton organisms such as mollusks, crustaceans, tunicate larvae, copepods, rotifers, nematods, young polychaetes, protozoans, diatoms, and eggs. They are also sometimes observed to eat small hydromedusae and ctenophores. These foods collect chiefly on the surface of the animal, where they become entangled in mucus. Food items are then passed on to the margins by flagellar action, where they collect on the lappets. They are then moved, again by flagellar currents, along eight separate canals, which are unique to this species of jellyfish. These canals branch off and run into the stomach, and they bring the food to it via the ring canal.
There is little known about the requirements for particular vitamins and minerals, but due to the presence of some digestive enzymes, we can deduce in general that A. aurita species consume carbohydrates, proteins, and lipids (Arai, 1997).
The Oregon Coast Aquarium reports that they feed their moon jellies brine shrimp.
 
Habitat:
The adult medusas are usually found in the open ocean. The young polyps can be found on pilings and floats in harbors and under rocks and shells in the low to subtidal zone in bays.
Their habitat includes the costal waters of all zones, and they occur in huge numbers. They are known to live in brackish waters with as low a salt content as 0.6%. Decreased salinity in the water diminishes the bell curvature, and vice versa. An optimum temperature for the animals is 9 - 19 degrees Celsius.

Range:
Worldwide distribution.
Atlantic Ocean, Pacific Ocean, Indian Ocean: Aurelia aurita are found near the coast, in mostly warm and tropical waters (but they can withstand temperatures as low as -6 and as high as 31 degrees Celsius). They are prevalent in both inshore seas and oceans.


Reproductive History:
The sexes are separate with the moon jelly. The eggs develop in gonads located in pockets formed by the frills of the oral arms. The gonads are commonly the most recognizable part of the animal, because of their deep and conspicuous coloration. The gonads lie at the bottom of the stomach. The male broadcast spawns his sperm through a three foot sperm tube and the female takes in the sperm so fertilization is internal. After being fertilized, the female broods her developing embryos on her oral arms until they reach the planula stage which is free swimming. The panula larvae remains in the plankton for a short time until it settles on a solid substrate (attaches itself onto a reef ). After settling, it grows into the polyp stage called a scyphistoma which feeds on small zooplankton in the typical polyp (sea anemone) fashion. Eventually the polyp undergoes a transformation called strobilation in which one polyp buds off several tiny jellyfish. The small jellyfish that bud off are called ephyra (juvenile medusa). When these ephyra grow larger they are called medusa. This takes about four to five months.
Sexual maturity in Aurelia aurita commonly occurs in the spring and summer.

Behaviour:
Their behaviour depends on a number of external conditions, in particular, food supply. Aurelia swim by pulsations of the bell-shaped upper part of the anima. Swimming mostly functions to keep the animal at the surface of the water rather than to make progress through the water. They swim horizontally, keeping the bell near the surface at all times. This allows the tentacles to be spread over the largest possible area, in order to better catch food. The coronal muscle allows the animal to pulsate in order to move. Impulses to contract are sent by way of the subumbrellar nerve net and are nervous in origin. The Moon Jelly has rhopalial centres, which allow it to control the pulsations. As the oxygen rate in the water goes down, so too does the respiratory rate of the jellyfish.
Medusa A. aurita can survive in polluted, anoxic water environment that has low nutrients supply (J.E. Purcell, et al. 2001)

Natural History:
The life cycle begins when moon jellies spawn. Polyps are usually first seen in February and then they strobilate in March. The ephyra from strabilation grow to adult size, reproduce and usually die by July. Most live only five to six months. Some live another year reproducing continuously. Data from the Oregon Coast Aquarium state that they can live three years or more in captivity.

Predators:
The death of the organism sometimes is brought by after reproduction, leaving the gonads open to infection and degradation (Arai, 1997). A. aurita have been food for a wide variety of predators including the ocean sunfish, Mola mola, loggerhead turtles, Caretta caretta, and the hydromedusae Aequorea victoria (Arai, 1997). Another cause of death is by fisheries for food.
There are possible metazoan parasites that attack A. aurita (Arai, 1997).


Conservation:
Status: no special status
They are very plentiful.