Just when you think you've heard it all, two recent research projects have discovered that honeybees have emotional lives and the nervous system of jellyfish and their behavior is far more complex than previously thought. Melissa Bateson and her colleagues have shown when honeybees are stressed, they display an increased expectation of bad outcomes. In other words, they become pessimists. When similar behavior is observed in vertebrates it's explained as having an emotional basis. The bees also showed altered levels of neurochemicals (dopamine, serotonin, and octopamine) that are associated with depression.This fascinating study shows that we need to be very careful making claims that invertebrates do not have emotional lives or feelings. In fact, there are marked similarities with vertebrates. Bees also outperform computers in solving the traveling salesman problem.
Jellyfish also have been in the news. They're much more than plasma and poison. These ancient multiorgan carnivorous animals are much more than mindless protoplasm. They possess a complex visual system that allows them to navigate the swamps in which they live and have what can be called a central nervous system and a brain. They're not merely passive floaters and the behavior patterns they exhibit are not simple reflexes but rather well organized. For example, when they're staring into the heavens they're actually seeking navigational guidance.
The more we study other animals the more we learn about their fascinating lives. How exciting it is to learn more about animals who we typically write off as being "lower" and not especially intelligent or emotional. Fish also are far more complex than previously thought and are now considered to be very intelligent and sentient beings (see also). Indeed, drawing lines between "higher" and "lower" species, a practice called speciesism, is fraught with errors and shouldn't be done. Animals do what they need to do to be card-carrying members of their species and we need to remember that numerous nonhuman animals outperform us in many different ways.