Freshwater Jellyfish
Interesting Facts about the Freshwater Jellyfish
The freshwater jellyfish is not actually a jellyfish in the true sense of the word. They are different in several ways from the marine or salt water jellyfish.
The freshwater jellyfish sports a structure known as a velum on its ventral surface. The velum starts at the circular bell's edge and extends inward from there. Through the velum's hole extends the manubrium, at the end of which is the jelly's mouth. The reason the freshwater jellyfish is called a jellyfish is because it so closely resembles one.
Freshwater jellyfish only grow to roughly the size of a quarter when they are completely grown. They are shaped like umbrellas, and they have tentacles that look like strings around the edge of the bell.
This jelly has the typical tentacles that we are accustomed to seeing on actual jellyfish. They also sport nematocysts on their tentacles, which they use to catch their prey. They are normally almost translucent, with a green or white tinge to the coloring. Their sex organs hang from their underside, and they are not translucent, which makes the freshwater jellyfish easier to spot.
These jellyfish are usually found in water-filled quarries or pits, man-made lakes or freshwater lakes. They prefer calm water. You can occasionally also see them in recreational boating and fishing areas. They have even been spotted in the Tennessee, Ohio and Allegheny rivers. But generally they would rather stay in standing water.
Freshwater jellyfish, much like their marine cousins, maintain a diet of microscopic animals known as zooplankton. These tiny animals are found everywhere throughout watery areas.
Generally you see freshwater jellyfish in the later summer months. August and September are the two months when they are seen the most often in the eastern United States. At this time of year, food is easy to find, and the water is warm. The jellies swim gently or float immediately below the water's surface. You can see them quite easily with the naked eye. Sometimes they will come up to the surface in large groups that are referred to as “blooms”. They are especially easy to spot on sunny days.
It is unknown whether the stinger of a freshwater jelly can penetrate the skin of a human, but some people say that have been stung by them. No hard evidence exists that proves this claim, however.
Freshwater jellyfish have been spotted in most areas of the United States – in 43 states, to be precise. When the weather turns cooler, these jellies close up their bodies, and become almost non-active until warmer temperatures arrive.
Some people have tried to keep freshwater jellyfish in aquariums, but they don't do very well. You have to have a very sensitive filter system that won't suck the jelly into it. You also would not want a current in your tank, as these jellies prefer calm waters.