A is For Atlantic: Jellyfish

·         They were the first group created after sponges, which was a huge evolutionary step.

·         They are filed as cnidaria, which include jellyfish, cubozoans, corals, and sea anemones.

·         Characteristics:

o   Radial symmetry

o   Oral and aboral surfaces

o   Primitive nervous system

o   Nematocysts (stinging cells)

·         Cubozoans are box jellyfish, and are a different species. They have a distinct box shape with four tentacles. They are much faster than jellyfish and even have primitive eyes that give some vision. They are far more advanced than jellyfish, which just float with the currents.

·         Jellyfish have statocysts around the edge of the bell to sense gravity to tell them when to direct themselves up and down.

·         Jellyfish do not float in colonies intentionally, but rather currents usually group them together. Thus, if you see one jellyfish when you are at the beach, there will most likely be more.

·         They are made up of 95% water and the rest is mesoglea, which is the jelly-like substance.

·         Their mouth and the anus are the same.

·         Some jellyfish change phases throughout their life between the medusa (jellyfish) and polyp (sea anemone) stage. Stropulation is when they change from a polyp to a medusa.

·         Most of them eat zooplankton, which leaves little food left for the fish. This makes the fish have a shortage of food, which then in effect affects the fishing industry (us). Therefore, large groups of jellyfish are not good for humans.

·         There are comb jellies (ctenophores), which have 8 rows of cilia. They pump through the water, not float.

·         The jellies that we usually see on east coast beaches are called one wind sailors. They have a tougher than jelly feeling bell. They are related to the Portuguese Man of War, which is a colonial species. Because it is a colonial species, they have specific tentacles for feeding, reproduction, and stinging. Each appendage is its own organism. Thus, if one part breaks off, it may regenerate a new organism.

·         Jellyfish sting to catch prey (offensive).

·         Some jellyfish stings are fatal, such as the sea wasp in Australian waters.

·         Some jellyfish have the potential to have a six foot wide bell and 100 foot long tentacles.

·         Jellyfish are not affected by the various pressures in the different levels of water because they  are mainly composed of water. They can move up and down in the water levels, but they tend to remain in the top 200 meters because that is where all of the zooplankton reside.

·         They are eaten by some sea turtles, such as the leatherback, and some fish, such as the sunfish in Japan.

·         It is not uncommon to be stung by a jellyfish at night, because they typically vertical migrate to the surface during the night to feed without worrying about predators.