Lake Ouachita Has Freshwater Jellyfish

 These bell-shaped hydrozoa (craspedacusta sowerbyii) are translucent with a
 white or green tint and are about the size of a quarter when fully grown.

  They are umbrella shaped and have a whorl of string-like
 tentacles around their circular edge (ring canal).
 

Picture courtesy of the Indiana University of Pennsylvania

The tentacles contain hundreds of special cells called cnidocytes.
The cnidocytes contain the nematocysts that are used to capture prey.

The jellyfish are usually somewhat translucent with a whitish or greenish tinge.
Often, large flat sex organs called gonads hang from the underside of the jellyfish.
These organs make the jellyfish easier to spot because they are not translucent.

Like true jellyfish, they do have stinging cells (cnidocytes).
This mechanism is designed for feeding, as the cnidocytes are utilized
 to paralyze macroinvertebrates and even small fish.

 There is no "hard" evidence that these organisms can penetrate human skin
 (though some have claimed otherwise).

 August and September are peak months for jellyfish sightings
when Lake Ouachita water is warm and food is abundant.

The jellyfish will be floating or swimming gently just below the surface of the water.
 They are easily seen by the naked eye.

They often surface in large numbers called "blooms".
Sunny days are especially good for spotting jellyfish.