Cassiopeidae

''Cassiopea'' (upside-down jellyfish) is a genus of true jellyfish and members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow mangrove swamps, mudflats, canals, and turtle grass flats in Florida, the Caribbean and Micronesia. The medusa usually lives upside-down on the sea floor in shallow areas, which has earned them their common name. These jellyfish partake in a symbiotic relationship with photosynthetic dinoflagellates and therefore, must lie upside-down in areas with sufficient light penetration to fuel their energy source, which also involves certain elements and minerals such as carbon. Where found, there may be numerous individuals with varying shades of white, blue, green and brown. Furthermore, these creatures have unique characteristics involving significant aspects of reproducing with their oral disc, processes in their sleep state, and the use of water currents while swimming and capturing prey that set them a part from many other species. They also have toxic proteins in their mucus, which affects all other creatures in the water along with them.

Species

According to the ''World Register of Marine Species'', this genus includes 12 species:

* '' Cassiopea andromeda'' (Forsskål, 1775)—Indo-Pacific, introduced in the Mediterranean
* '' Cassiopea culionensis'' Light, 1914
* '' Cassiopea depressa'' Haeckel, 1880—Western Indian Ocean off the African coast
* '' Cassiopea frondosa'' (Pallas, 1774)—Western Atlantic, Caribbean Sea
* '' Cassiopea maremetens'' Gershwin, Zeidler & Davie, 2010—Western Pacific Ocean, off the Australian Coast
* ''Cassiopea mayeri'' Gamero-Mora, Collins, Boco, Geson III & Morandini, 2022
* '' Cassiopea medusa'' Light, 1914—Pacific Ocean, Philippines and Palau Region
* '' Cassiopea mertensi'' Brandt, 1838—Pacific Ocean Southern Micronesia
* '' Cassiopea ndrosia'' Agassiz & Mayer, 1899—Pacific Ocean, Australia and Fiji
* '' Cassiopea ornata'' Haeckel, 1880—Pacific Ocean, Palau, Philippines, Okinawa
* '' Cassiopea vanderhorsti'' Stiasny, 1924
* ''Cassiopea xamachana'' Bigelow, 1892—Caribbean Sea and the Northern Atlantic Area of the West indies

Sex life

''Cassiopea'' individuals are either strictly male or female, also known as being gonochoristic. Unlike humans, this species has a gastrovascular cavity, meaning their digestive system only has one opening. This is where the fertilization of their babies primarily occurs, and happens at a decently quick rate. After fertilized, the embryos are expelled and attached onto their oral disc, which is commonly known as their mouth. The eggs are present on this surface for 48 hours after they are fertilized. By the 96-hour mark, they elongate and become polyps, meaning they already are beginning to look like their species.

Sleep state

Certain species of ''Cassiopea'' have been observed to enter a sleep state and displays three primarily characteristics during that time. These are quiescence, also known as a state of inactivity or dormancy, delayed responsiveness to stimuli (or sensory depression), and being able to partake in homeostatic regulation whilst asleep, or not being highly affected by the outside environment and remaining stable. Furthermore, they are the first animals with no central nervous system to have been observed sleeping. When ''Cassiopea'' are provoked, they release mucus that contains toxic proteins. More specifically, ciliated structures that have been shown to be considered parasitic larvae.

Swimming

The process of ''Cassiopea'' swimming is quite unique to jellyfish themselves. They create their own water currents to propel when changing direction through the use of contracting a part of their body called the bell, which is the mushroom-shaped structure. This contraction originates a whirlpool at the bell and are broken through the pressure exerted on the oral arms. Also, the jellyfish move in a constant flow, which pushes towards the animal and having a upward flow above them.

Nutritional requirements

These jellyfish are more unusual than most species regarding their nutrition. Upside down jellyfish do not gain much nutrients from feeding from the waters around them, rather they need a significant amount of minerals to support their carbohydrates and lipids. This allows for them to continue to grow and prolong sexual reproduction. Even so, the process behind them feeding is still relatively unknown to many. The major gap of knowledge is how there is an ongoing process of biosynthesis and carbon flow, which are believed to be complex metabolic modifications within the jellyfish. Furthermore, they have endosymbiotic algae living inside of them, allowing them to photosynthesize as a whole organism. Recently, the jellyfish have been more widely known for this symbiotic relationship because of them being able to autotrophically assimilate with the element, carbon. With everything aside, glycerol is the dominant photosynthetic that they are producing, specifically glucose.

Feeding habits

The ''Cassiopeia'' species has a unique way of catching their prey. They do this by pulsating to move the water around them and pull in the prey under their bell. Once the prey is under their bell, they use their oral arms to clutch the prey. The oral arms hold the prey in place by using the small oral vesicles attached to the arms. Once they are grasped, the jellyfish turns the prey into little fragments to be consumed. Once they have reduced the size of their food, the particles go into their secondary mouth, then is digested by their cilia. Typically, they feed on crustaceans, nematodes, and eggs, which makes them an opportunistic predator. Even so, in a lab environment, ''Cassiopeia'' are fed⁣⁣ Artemia salina⁣⁣, which is a type of shrimp.

References

External links

Photo of a Crab carrying an Upside Down Jellyfish (Cassiopea andromeda)





{{Taxonbar, from1=Q289354, from2=Q2941298

Cassiopeidae
Scyphozoan genera