Nutrition

     Cassiopea xamachana get most of their nutrients from symbiotic relationships with dinoflagellates. More specifically, the Cassiopea generally co-exist with the genus Symbiodinium. Both parties are negatively affected when the two species live apart (Thornhill et al. 2006). Dinoflagellates carry out photosynthesis that provides Cassiopea with energy. They also provide for the jellyfish by supplying them with glycerol, alanine, and glucose. This nutrient acquisition via a host occurs much like it does in corals. Also, all necessary metabolic processes can be carried out with the aid of dinoflagellates. Without their symbiont, Cassiopea are much smaller and less efficient and obtaining nutrients. It is not yet known whether or not the jellyfish are able to survive without their symbiotic partners (McGill et al. 2008). One factor that influences this is bleaching. This is when ocean temperatures raise, and dinoflagellates lose their ability to photosynthesize (McGill et al. 2008). It is also a problem when it keeps Cassiopea from being able to provide for dinoflagellates. It makes the jellyfish too small to support their photosynthetic Symbiodiniums (McGill et al. 2008).

     Another way that Cassiopea get their nutrients is through zooplankton, phytoplankton, copepods, and detritus. This form of nutrients is called particulate organic matter; also known as POM. They also take up dissolved organic matter, which is also referred to as DOM. This is why mangroves are great places for jellyfish to live (McGill et al. 2008 and Santhanakrishnan et al. 2012); because they are swamps with dead plant life that supports many organisms. Besides organic, they also take up inorganic nutrients from the surrounding environment (Niggl et al.2009).

     The method that these jellyfish use to capture their nutrients is part of what makes them different from other classes of jellyfish. They use their oral arms to generate a strong current over the mouth of their bells. Because jellyfish live in habitats with little to no water currents, they must bring the food to themselves. They need to generate a current since they are semi sessile creatures. This means that most of the time they stay in one place and are mainly immobile. Instead, they are upside down with their arms and bells exposed to the sunlight. Another reason they create a low flow current is to test the water for prey. They are successful with these practices due to the length or their arms; their arms extend beyond the length of their bell. The complete mechanics of how these currents are generated have been studied in depth. It is known that the bell makes two contractions while the arms are flowing in sync with these actions. It makes a power stroke and a recovery stroke. These consist of a full contraction and a full relaxation (Santhanakrishnan et al. 2012).

     Another crucial piece of information about Cassiopea is that in many cases they are bio indicators. In water sources with low nutrient levels, the amount of phosphate the jellyfish uptake is closely monitored. This is because phosphate is a limiting nutrient and the amount of it the jellyfish take in correlates with how much of nutrients are in the water. After being exposed to an abundance of phosphate, the intake amounts by jellyfish decrease. If the water is saturated with nutrients for a length of time, the intake by Cassiopea remains low. As nutrition remains high, the jellyfish do not need to take in as much of the limiting phosphate. Their nutrient uptake depends heavily on what their symbiotic partners need. If they take in a minimum amount of phosphate for a long time, the water will have too high of a concentration of it (Todd et al.2006).