A crystal known as a “statolith” hangs under the eye, like a tennis ball hanging from a rope. Not only do the complex eyes give a means to visually navigate their environments, but in some cases, they allow jellies to detect gravity. Others, including box jellies (Tripedalia cystophora), have a more complex visual system complete with lenses, retinas and corneas. Some simply have what Janssen described as “eye spots,” which detect light, but little else.

Jellyfish eyes range from primitive to more complex. Here are six little-known facts she wants people to know about jellies. NewsHour science producers Nsikan Akpan and Julia Griffin recently took a trip to Baltimore to speak with jellyfish expert Jennie Janssen, assistant curator of the Blue Wonders exhibit at the National Aquarium. More than 2,000 species of “jellies” - as they are known in the scientific community - exist on planet Earth, but to many, the creatures remain a beautiful, but alien, oddity.

Jellyfish - the pulsing, jello-like balloons of the ocean - have fascinated beachgoers and aquarium visitors for generations.

Instal Gravity Oddity