Starfish Anemones (Nematostella vectensis) are capable of amazingly complex learning, scientists say. This is evidenced by their ability to remember the relationship between light and electrical impulse, according to Science Alert..

“This is exactly what is called associative learning.. Proof that even animals without a brain are capable of exhibiting complex behaviors through their nervous systems,” says senior author Simon Sprecher, a neuroscientist at the University of Friborg..

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Animals, including humans, with highly developed brains can easily associate a stimulus with a response and change their behavior.. For example, if you find that touching a hot stove causes pain, you do not repeat this action..

It is believed that this ability appeared as the development of the nervous system, which regulates the strength and plasticity of synapses in the brain.. But not all animals have brains.. Cnidarians like sea anemones and jellyfish have only a decentralized neural network. Therefore, scientists believe that they can only learn in non-associative ways..

To find out if this is true, scientists conducted classic experiments on the development of a conditioned reflex with light and electric current.. According to the authors of the work, studies conducted 40 years ago provided inconclusive evidence for non-associative ways of learning anemones, and no longer repeated..

In the new study, scientists randomly assigned groups of 10 or 18 star anemones to either paired trials, in which light and electrical pulses coincided, or unpaired trials, in which light and electrical pulses occurred out of sync.. The researchers used a small electrical impulse to force animals to retract their tentacles, either with or without light..

The scientists then tested the reaction only to light..

In the group that had previously been electrocuted at the same time as the light, 72% of the anemones only retracted their tentacles when exposed to the light.. This was more than twice the reaction rate (30%) in animals trained with electric shock and light at different times..

“Overall,” the authors write, “these animals showed a quantitatively and qualitatively different behavioral response compared to control animals that received unpaired stimuli.”.

However, what exactly causes such a reaction of animals is still unclear..