No brain, no problem. Jellyfish learn just fine

When it comes to learned behavior, even the simplest minds are capable of advanced thought. The Caribbean box jellyfish ( Tripedalia cystophora ), which doesn’t even have a brain, can alter its behavior based on past experiences, new research reveals. Scientists believe the creature uses this learning ability along with its astoundingly complex visual system to navigate the murky mangrove swamps it calls home. Scientists have known for some time that animals in the phylum Cnidaria—which includes jellyfish, corals, and sea anemones—are capable of basic forms of learning when repeatedly presented with a stimulus in their environment. They will either respond to it less (what’s known as habituation) or more (known as sensitization). Humans do this all the time—if you hear a sound over and over again, your ears might tune it out. In other instances, the sound may become difficult to ignore. Habituation and sensitization are types of so-called nonassociative learning, as they don’t require connections between two different stimulus types in order to generate a response. In contrast, associative learning, which involves linking different types of stimuli together to then modify behavior, is regarded as a more advanced kind of learning. Until recently, scientists believed that only animals with advanced nervous systems—such as humans and other mammals—could do it. Because a jellyfish’s nervous system is dispersed throughout its body, wit...
Source: ScienceNOW - Category: Science Source Type: news