I am writing a book, and I want to create either a sentient fungoid or plant and I wish for it to use hormones instead of neurons to transfer information. I'm not sure how this would work and affect the capacities of the plant/fungoid?
How would hormonal sentience work and affect the way a brain works in a plant or fungoid?
2$\begingroup$ Brains are darn expensive, if you don't have a good reason for one, you're going to want to expend that energy elsewhere. If you want a good biological grounding for your world, perhaps start with a cause/reason/need for low energy sessile organisms having one. Perhaps they are like barnacles and were once free moving? The crux is, it's all well and good knowing things, but unless that knowledge can be used to save you or have more offspring, natural selection isn't going to favour you. $\endgroup$– TroysephJun 6, 2016 at 7:49
1$\begingroup$ Of course it's your fantasy, and realism is never a requirement, I just assumed that was your angle. Also you don't need to be limited to plants and fungi, you can create your own biology which works very differently to ours on earth. $\endgroup$– TroysephJun 6, 2016 at 7:55
$\begingroup$ And don't forget that you have no obligation to be realistic nor scientifically accurate to an extreme if you don't want to. Marvel's Groot and Tolkien's ents are examples of intelligent plantoids, and no one questions the biology involved in them. $\endgroup$– The Square-Cube LawJun 6, 2016 at 11:33
It's possible, doable, and there is real world research on plant intelligence.
There are a few "problems" with this kind of intelligence, though. Comparative problems, having to do with speed.
Let us talk about something more basic than sentience. I think we can agree that consciousness is a prerequisite - you have to be aware before you can think "I am". We still know little about consciousness, but it's all about computing and how data is moved around a colletion of parts.
In our case, we use neurons. It may be that one day we will replace them with electronic parts. What neurons and electronics have in common is that they use electricity. For neurons, this means a signal can travel up to 120 meters per second (1 meter is about 1.1 yards, or a bit more than 3'3"). With electronics instead of neurons, an electrical impulse will move at a considerable fraction of the speed of light.
In very laysman terms, it means that if I step on your foot, the pain signal will reach your brain in really short time, and you will be able to react practically instantly.
A plant or a fungus, though, which can't rely on electrical impulses and must communicate solely through chemical signals... Well, that might take some time.
If I kick the ankle of your fungoid, its ankle will start to produce the chemicals that signal pain. Now it doesn't matter if it has a brain somewhere or if its processing elements are spread wide over its body, it will take a lot of time for its circulatory system to distribute those signaling chemicals to its "neural" network. For a human sized fungus monster, this could take from minutes to hours, depending on your design - but it could be faster if your creatures have a heart to pump their fluids.
Now, the signal doesn't just have to reach the "neural" network. Each element must process its input, and communicate its processing result to the elements connected to it, many times.
Your fungoid might start calling me names days after I've kicked it.
For a creature like this, a mobile lifestyle would be a no-no. It's no good moving around if you'll only react to the simplest obstacle in your path only on the next day.
Of course, this is all assuming that your creatures are human sized. If they are small, the distance the chemical signals will have to travel before a reaction can be taken will be shorter too. Remember, bacteria and protozoa have no neurons, and they react to their environment in reasonable time (usually - but not always).
$\begingroup$ From a biological point of view, being able to react to external information is always useful to survival hence it is no surprise that plants have complex reactions to stimulus such as insect attack. This can be considered intelligence (a calculated response to complex information input) however it in no means implies sentience or consciousness. $\endgroup$– TroysephJun 6, 2016 at 7:44
2$\begingroup$ @Troyseph I am not implying that plants are conscious or sentient. I'm taking the so-called "plant intelligence" being studied nowadays as a basis to justify the viability of "intelligent" plantoids in a fictional universe. $\endgroup$ Jun 6, 2016 at 11:29