Aurelia Aurita is also called as moon-jelly or jelly fish. It is the most common jellyfish that can be found in the coastal waters of tropical and temperate oceans all over the world. It is an inshore genus which you can find in estuaries and harbors. They are usually abundant in spring but disappear in July. Let us look at the distinct characteristics and life history of this marine invertebrate.
- Shape, Size and Color: Moon-Jelly can be effectively perceived by its delicate umbrella-shaped body with four horseshoe-shaped gonads on its upper surface and four long and narrow oral lubes hanging downwards from the lower surface. The umbrella is divided into a convex surface and a concave lower surface, also known as exumbrellar surface and subumbrellar surface respectively. The body of the Aurelia is transparent and bluish white in color, whereas the gonads are pinkish or reddish and so they can be seen clearly from the body surface. These invertebrates can range between 5 and 40 centimeters.
- Habitat: Their habitat includes the coastal waters of all zones. Atlantic Ocean, Pacific Ocean, and Indian Ocean are homes to these aquatic animals. They can withstand temperatures as low as -6 degrees Celsius and as high as 31 degrees Celsius. However, the optimum temperature for them is between 9 and 19 degrees Celsius. Waters with salt content as low as 0.6% are favorable for them to live in. As the salinity of the water decreases their bell curvature diminishes and vice versa.
- Biology: Moon-jelly is carnivorous and sustains itself on planktonic animal groups like molluscs, young worms, crustaceans, and copepods. The plankton gets stuck in the mucus layer which covers the body of the jellyfish. Small hair-like structures called ‘cilia’ that can be found on the body of the jellyfish produce currents by beating and these currents transport the plankton that is stuck in the mucus layer towards the edge of the ‘umbrella’, where it is removed using the oral arms and passed to the mouth. In the Aurelia aurita, the sexes are separate and the sperm is taken into the female’s body by means of the mouth. The eggs develop in the pockets formed by the frills of the oral arms. This aquatic animal can also reproduce by asexual methods.
- Behavior: The behavior of Aurelia aurita depends on a number of external factors, mainly the food supply. They swim by the pulsations of the umbrella-shaped upper part of the anima. They mostly keep at the surface of the water and swim horizontally, keeping the bell or the umbrella near the surface at all times. This helps them to spread their tentacles over a wide distance to catch preys in the water. As the oxygen rate in the water goes down so does the respiratory rate of the jellyfish.
- Respiration and Excretion: There are no particular organs to perform the functions of respiration and excretion. Apparently, these procedures are performed by the entire body surface of the jellyfish. The gastro vascular framework achieves the respiratory goal by carrying oxygen and removing carbon dioxide with the current of the water and its circulation. The jellyfish comprises of almost 96% water and so the requirement of the oxygen by the medusa is very limited when compared to its weight. The gastro vascular system also removes the excretory matter.
Common Fish Parasite Is Actually a Micro Jellyfish
According to the researchers, microscopic parasites that are only a few cells large are essentially degenerated jellyfish. “When people think of an animal, they think of a macroscopic, multicellular, complex organism, and now they’ll have to expand their definition of an animal to include very simple microscopic organisms,” said study co-author Paulyn Cartwright, an evolutionary biologist at the University of Kansas. Researchers analyzed and studied myxozoans that are microscopic parasites known to infect the commercial fish as part of their life cycle. The genomes of these common sea pests revealed that they were in fact ‘micro-jellyfish’ complete with stinging tentacles. According to the findings published in Proceedings of the National Academy of Sciences, these parasites were highly reduced and stripped-down cnidarians.
Myxozoans consist of just a few cells and don’t have a mouth or a gut. They are closely related to medusozoans, the cnidarians that include jellyfish. The myxozoans also have the bell-shaped part that can be found in a traditional jellyfish as well. These parasites are also known to cause neurological problems in the commercial fishes where the fishes start swimming in circles, also known as the whirling disease. There are more than 2,180 species of myxozoans measuring 10 to 20 microns in width. Myxozoans exhibit an important jellyfish feature – nematocysts and the genes needed to make them. The researchers are trying to know more about their cell degeneration with the completion of technologies like whole genome sequencing.