Invertebrates Are Definitely Capable Of Learning! A Lot Of People Who Don’t Know Anything About Bugs

Invertebrates are definitely capable of learning! A lot of people who don’t know anything about bugs say they’re automata who just do everything by instinct like an if-then computer program, and they absolutely have not looked into it because there’s SO much literature on invertebrate cognition including learning. One of the neatest papers I’ve seen was about Drosophila fruit flies (there’s a ton of fruit fly literature cuz they’re a common lab animal). So when a female fruit fly is exposed to parasitoid wasps, she will start laying fewer eggs. These researchers showed that fruit flies who have been exposed to wasps can communicate the presence of a threat via wing movements to other female fruit flies, and those flies will start laying fewer eggs too even if they haven’t seen the wasps at all, an example of social learning.

But what’s more: they can communicate threats like this not just with flies of their own species, but with flies of closely related species too. If the species are too distant, they stop being able to communicate as successfully HOWEVER these authors showed that if you house a bunch of flies together in mixed-species groups, afterwards their success at communicating goes up! This suggests the existence of a fruit fly “language” which differs between species, but which they’re capable of learning other species’ languages as well! Sources: 1, 2

see also this very scientific diagram from here:

One interesting thing about those studies is that they found that if you raise a fruit fly in isolation from hatching, it won’t be able to communicate as well. This suggests that there’s a critical period of socialization which flies require to learn how to do communicate properly and without it their ability to do so is impaired. (I believe there’s other studies on how other social interactions are affected by social isolation but I haven’t read them; again there’s sooo much fly literature ^^)

Another cool one I’ve seen is on antlion larvae, who hunt by digging pits and then waiting in the middle for ants and other bugs walking by to fall in. It’s generally thought that sedentary animals have fewer cognitive capabilities than mobile ones, due to their less demanding lifestyle, however these studies (which I’ve only skimmed) have been carried out which demonstrate that they are still capable of learning. Specifically, they can be taught to anticipate and identify approaching insects based on vibrations in the sand, and will subsequently adapt their behavior to hunt more efficiently! Even animals with what seems like a simple feeding behavior are still very capable of modifying it, which makes sense evolutionarily; while obviously different animals will require different levels of intelligence, you can imagine in a lot of cases that being able to modify your behavior based on experience is distinctly advantageous. Source 1, 2

Not an arthropod, but another bug that there’s been a lot of research into is Lymnaea pond snails, which are another common model organism for studying neurology and cognition. A ton of work has been done on their capabilities for associative learning, i.e. classical conditioning (“dog learns to salivate at the ring of a bell”) and operant conditioning (“rat learns that pressing a button gives food”). It’s been found that their ability to learn is actually a lot more complicated than just those simple kinds of stimulus ↔ response. They can take stuff they’ve learned in stressful situations (simulated experimentally by exposing them to the smell of crayfish, which eat snails) and generalize it to situations beyond just the original context, which you can imagine must be pretty important for surviving in the wild. Conversely, they can also place memories in context: when taught stuff in the presence of both crayfish smell and carrot smell, subsequently they will recall what they’ve learned in response to the carrot smell alone; in other words, they’re not just learning “carrot + crayfish smell”, but “carrot smell = crayfish smell”, placing their memories in the broader context of their environment (which again, must be helpful for survival). So they can not just learn but pretty flexibly as well! Sources 1, 2, 3

This isn't a bug at all but pretty recently there was a study that found that box jellyfish are capable of associative learning. This one research lab has done a lot of work into vision in the Caribbean box jellyfish (they have eyes btw) on both a behavior and a neurological level and have found a lot of cool things, like that these box jellyfish use their vision to navigate through their habitat of mangrove forests, and that though they don't have a brain as such, they do have a central nervous system in the form of a ring nerve connecting four small clusters of neurons that process and combine input from their eyes. I can't actually read the paper (paywall :P) but last year they did an experiment where they put jellies in a tank with darkened bars on the glass to simulate mangrove roots. Normally the jellies gauge the distance to a root by how dark it appears and then swim around it when they get near; however the bars in the experiment were colored so that they looked like they were farther away than the wall actually was. At first the jellyfish kept bumping into the all, but after several rounds of trial and error they began to avoid them, indicating that they were able to learn from the experience! Jellyfish! Aaaaa nature is so cool. Source 1, 2, 3

I have a question! About bugs and arachnids and all them. Sorry to lump them all into one category, but I'd rather not make the same post multiple times.

My question is: Can they learn "tricks?"

By this I mean are they capable of learning, in general, I suppose. Like mice in a maze, magpies with a rock.

Also, what sorts of things have they learned? How do they learn (like watching others or from experience)?

I ask because it's something that really interests me. I know the ability to learn doesn't add or subtract value from a being, it's a curious thought as I know very, very little about beetles, and spiders, and bees, and so on!

Do they just know how to do things because it's all their kind have done since the beginning of them? Do they have to learn or are capable of it?