Cnidarians are exclusively aquatic animals that, although the greatest diversity is found in marine ecosystems, some may be present in freshwater bodies. Its distinctive feature, in addition to its peculiar body shapes, is the presence of cnidocytes, cells specialized in the production of toxins that they use to capture their food. Within this group of animals we have various types of jellyfish, one of them belonging to the scyphozoa class, which only live in marine waters and are known as true jellyfish. One of these is the moon jellyfish (Aurelia aurita), about which we present information in this file on our site.
Characteristics of the moon jellyfish
Next we will present the main characteristics of the moon jellyfish:
- The colorationexternal is transparent.
- Internally there are some bluish structures: that can form other shades and correspond to the animal's gonads, which have a ringed horseshoe shape.
- The mantle has a diameter ranging from 10 to 35 cmabout.
- The tentacles are small: they come out towards the side of the bell and measure between 1 and 5 cm.
- In the lower part of the bell it has four oral arms: which are provided with cnidocytes or stinging cells, where the nematocysts or secretory organelles.
- They have a diversity of cilia: which are structured around the bell.
- It lacks specialized respiratory structures or organs: to carry out this process, it does so by means of diffusion between the external tissue of the bell.
- It enters oxygen-rich water: it does so through its gastrovascular cavity and through that same means it expels the oxygen-deprived one. So that's an additional way to get the compound.
- Also no brain, particular digestive system, circulatory and excretory: instead, it has a series of tissues or structures to fulfill these functions, for example, radial canals to transport food and a nerve network which is involved in various processes. Discover other Animals without a brain: names and characteristics, in the following article on our site.
- Internally It is made up of mesoglea: the tissue that characterizes cnidarians and serves as a hydrostatic skeleton.
Moon jellyfish habitat
The moon jellyfish is a cosmopolitan type cnidarian, which is distributed in all the world's oceans, except the Arctic. In this sense, it is present in practically all marine areas in both North and South America, Asia, Europe, the coasts of Australia and, although to a lesser extent, in Africa, there are estimates of its presence in some areas.
This type of true jellyfish can live in coastal ocean waters and also in tropical areas, so its temperature range is between 6 and 19 o C, although the optimal value for its development is 17 oC. A particular trait of the moon jellyfish is that, unlike others, it can live in waters with very low salinity , even less than 1%, but they thrive better around 40% s alts.
Regarding the depth levels, it can vary considerably, since it is located in the levels between the surface and 200 meters, an area known as epipelagic and also in the mesopelagic that reaches up to about 1,000 meters deep.
Moon jellyfish customs
The moon jellyfish, depending on the availability of food, temperatures and salinity conditions, group together forming large proliferations in certain areas. Jellyfish in general are excellent swimmers and this species uses the water propelled through the bell to move horizontally towards the surface.
Although research is lacking, it is estimated that moon jellies are capable of communicating chemically through substances they secrete in the water. On the other hand, they have structures in the mantle that allow them to detect light, depth and even gravity.
An extremely interesting aspect that has been reported by a study [1], is that jellyfish of the genus Aurelia, including the moon jellyfish, are the evidence that these animals can have reverse transformation, from the phases of sexually mature adults to the form of polyps, which would make them more young instead of getting old. This possibility has been reported in very few species.
Moon jellyfish feeding
The moon jellyfish is a carnivorous animal, so it is an active predatorWhen they perceive their potential prey nearby, they use the structure similar to a harpoon known as nematocysts, with which they inoculate a toxic substance that paralyzes the animal captured. Then, it uses its oral arms to carry the prey to under its bell where a hole is located through which it is inserted.
Among the prey on which the moon jellyfish feeds we find:
- Small fish
- Copepods
- Eggs
- Mollusks
- Other jellyfish
- Plankton
Moon jellyfish reproduction
These jellyfish are sexually dimorphic, that is, there are differences between males and females. In them there are no courtship actions, nor are any hierarchical organization related to reproduction reported.
Has two reproductive stages:
- A sexual phase: the adult male releases sperm filaments into the water which, close to the female, and with water of the currents, they are introduced into the gastric bag of the female with the help of the cilia present in the bell. Once inside, they fertilize the ovules, which are later released into the water. From the fertilized eggs, planulae are formed, which are free-living and swim, thanks to the presence of cilia, in search of a substrate on which to adhere.
- An asexual phase: after they attach and transform into polyps, which reproduce in a second asexual phase. Polyps mature into strobili, which go through different stages to form fully formed juvenile medusae.
The reproductive process of the moon jellyfish, and in general as occurs with the group of jellyfish, depends on the factors of the aquatic environment, such as salinity, temperature and availability of food. The entire set of stages has a duration between 4 to about 6 months approximately.
Conservation status of the moon jellyfish
The moon jellyfish is not included in any list of endangered animalsIn fact, in some areas, due to its high proliferation, it is considered a problem because it affects certain human activities. However, almost no marine animal escapes the effects of climate change and, in general, other effects of anthropic origin, which is why we must not stop monitoring this jellyfish and other species in general, since they play important roles within the ecosystems.
