Box Jellyfish Have Eyes, Allowing it to See the World Above

According to an article published on April 28, 2011 in Current Biology, box jellyfish may be more complex than what meets the eye. Though it is well known that the jellyfish is a much simpler organism in comparison to a human, box jellyfish have no fewer than 24 eyes of four different kinds. Four of these eyes, called the upper lens eyes, always peer up out of the water, regardless of how the rest of the organism is oriented. Since box jellies live in mangrove swamps, it was hypothesized that the upper lens eyes help navigate the jellyfish around their environment. Anders Garm of the University of Copenhagen said, "It is a surprise that a jellyfish - an animal normally considered to be lacking both brain and advanced behavior - is able to perform visually guided navigation, which is not a trivial behavioral task. This shows that the behavioral abilities of simple animals, like jellyfish, may be underestimated." Scientists have known that box jellies have a unique array of eyes, which help the animal respond to light, avoid obstacles, and control their rate of swimming. When studied, the researchers noticed that the jellyfish used their upper lens eyes to navigate their way by means of looking at the canopy of mangrove trees. When the canopy was obscured from their vision, the box jellies could no longer get around and did not move. Garm says, "Instead of having a single pair of general-purpose eyes like most other animals, box jellyfish have several different types of eyes used for special purposes. This means that each individual eye type is dedicated to support only a limited number of behaviors. The eyes can then be built to collect precisely the information needed, minimizing the need for further processing in a big brain. The automatic orientation of the upper lens eyes to constantly look through the water surface is a clear example of this."

I thought this article was really interesting because I, like I'm sure most people do, assumed that jellyfish were stupid creatures that cannot do anything complex because of their simplicity. Also, I thought it was REALLY cool that they have so many different types of eyes, each with its own special purpose. It makes sense why each type of eye has only a certain number of functions, though, as Garm said. It cuts down on the jellyfish's necessity to process that information through the brain. So that explains why jellyfish have such a small brain and can still perform complex behavioral tasks, like navigating through a mangrove swamp. I'm pretty sure I wouldn't be able to navigate myself through a mangrove swamp, and I'm much more complex than a jellyfish! Props to the box jellies. =]