Although jellyfish don't have brains, scientists have found a way to read their minds -- in a way of speaking.

Through clever genetic tinkering, we can now see how neurons in a tiny transparent jellyfish work together to make complex autonomous movements, such as catching and eating prey.

Clytia hemisphaerica is the perfect model to study this behavior. Because this particular species of jellyfish is so small (only about a centimeter in diameter), its entire nervous system can easily fit under a microscope.

Its genome is also fairly simple, with its transparent body containing only about 10,000 neurons, making it easier to track neural information.

When researchers genetically engineered the Hemi-jellyfish C. hemisphaerica to make its neurons glow when activated, they discovered an "unexpectedly structured neural organization."

The jellyfish’s nervous system developed over 500 million years ago and has changed little since. The neurons in these "living fossils" are arranged more simply than in the brains of today's animals.

Without a centralized system to coordinate all the movements of a creature, how can it accomplish anything? The new study shows that Lobelia's neurons are arranged in an umbrella-like network that closely resembles its body.

These neurons are then further divided into slices, almost like a pie.

Each tentacle on the edge of the jellyfish bell is attached to one of the slices. So when a jellyfish's arm detects and captures prey, such as a brine shrimp, the neurons in the patch are activated in a specific order.

First, neurons on the edge of the pie slice send messages to neurons in the middle, where the jellyfish's mouth is. This causes the edge of the pie slice to turn inward toward the mouth, allowing the tentacles to follow.

At the same time, the mouth in turn "points" at the incoming food.

Within a minute of being introduced to the brine shrimp, the researchers found that 96 percent of the jellyfish attempted this "food transfer," with 88 percent success. Nearly all brine shrimp end up being eaten by organisms that use this feeding behavior.

To figure out which neurons specifically trigger this domino effect, the researchers deleted a type of neuron called RFa+ neurons at the edges of the pie slices.

When they did, the asymmetric inward folding of the jellyfish bell did not occur, nor did the transfer of the shrimp from tentacles to mouth.

"Thus," the researchers write, "RFa+ neurons are required for food-induced and chemical-induced edge folding. By contrast, swimming and folding are undisturbed, suggesting that other neuronal cell types control these behaviors.

To understand how the neurons that control the mouth communicate with the neurons that control the jellyfish bells, and vice versa, the researchers began surgically removing certain body parts.

When the jellyfish's mouth was removed from the equation, the creatures kept trying to pass food from their tentacles to their nonexistent mouth.

Even with the jellyfish's tentacles removed, chemical extracts from shrimp introduced into the tank could still trigger the mouth to turn to the food source.

The findings suggest that the behavior of certain jellyfish is coordinated by groups of neurons that are functionally organized around the periparacarpet. For example, the network of neurons that connects a jellyfish bell to its mouth could also connect to the digestive system.

When the jellyfish in the study were deprived of food, the researchers found that they caught their prey faster than when they were less hungry.

This suggests some kind of neurofeedback that lets the jellyfish "know" it needs to fill its digestive system, putting other specific"feeding" networks on high alert. "

If this hierarchical view is correct, coordinated behavior in organisms lacking a central brain may emerge by duplicating and modifying smaller autonomous modules to form functionally interacting supermodules."

How these interactions are achieved remains to be determined.