My dear Doctor,

Having recently read your musings upon the nature of the Carrier Snail and the Fungus which grows upon it, I was quite startled to see that you had missed a quite important Law of Nature. Creatures do not invest in change unless there is a benefit.
I draw your attention to certain frogs of the swamps and jungles. The Poison-Spear Frog. Hemmelson’s Pixie-Eating Frog. There are a great variety of these species all through the lands, all marked by vividly bright patterns on their skins. These serve no good as camouflage, therefore must serve the opposite purpose. They ‘warn’ predators away. It stands to reason that a creature from underground, as your mushroom and snail appear to be, would benefit not at all from bright colors, but illumination might just stand in for this in the dark places underground.

Though biology is not my strong suit, the bright colors bring to mind the colorful and poisonous species of the tropics. Advertising one’s nature brings more protection than the actual effect! But given the unique nature of the Park’s ecosystem, there may be a different reason which only you, Doctor, are in a position to discover.

Once again your good and ingenuous nature lead you astray, my dear friend. So easily do you put aside the hypothesis of parasitism in favor of a more benevolent explanation! But consider the dispersal that a mycoid would gain from spreading not on the back of a sluggish snail, but on the claws of a phototropic avian or bat! The relative advantage is not to be compared.

Surely the true or at least primary fellowship here is with the snail’s predator, immune to the toxin of the mycoid. The only puzzle here is the predator in question. The avoidance by moth pixies is somewhat of a puzzle, as these would be a natural vector. However, it may be that only some of the many varieties will serve, or that they not resistant per se, but are cunning enough to avoid the poison. K. Wolus has spoken of their use of toxins on weapons; perhaps the interaction is deeper even than might reasonably be extrapolated here.

Your servant,
Richard

As usual, Richard, you poke holes in my theory with ease. I would curse you for it, but your theory holds water. It does seem true that a snail would make a poor spore dispersal mechanism in the presence of avian methods such as you describe. Perhaps the matter requires more thought. I believe it may be necessary for me to seek out subterranean passage to answer this matter. I will have look through my books to learn if there are any known cave entrances to be found nearby.

However, regarding your assertion that the moth pixies avoidance is based on cunning and not instinct, I must politely disagree. The assertions of K. Wolus and others in his camp that the moth pixie has anything more than a base (albeit higher than average) animal intelligence has not borne out in my research. It is true that they will on rare occasions demonstrate simple tool use, but poisoned weapons? Such an idea stretches my credulity a bit too far.

I am no expert on the fungal realm, but I have found a few sources that report bioluminescence to be quite frequent in mushrooms of the genus Mycena. Specimens of this genus are often exceedingly small, a few millimeters in diameter. Some are reported toxic, though I have not found much detail on this. My sources were quiet on the evolutionary reasons for the luminescence of these fungi; they do not appear to have any particular affinity for subterranean habitats.

Dr Heineman makes a good point, but I can suggest a possible answer. Your gastropod would certainly distribute the spores far less widely than a fast areal creature, but it would be far more likely to bring them into suitable environments, moist and rich in dead plant matter.

Dr. Roundbottom –

Good work on your investigation of the carrier snail. I am, frankly, relieved to see you swimming in shallower waters than in your previous postings regarding the wraith.

Consider again the glow giving of by the poisonous mycoid. Would not such a glow attract the attention of a predetor? Would they not be especially visible from the air, even at a distance?

Heineman, dispite his previous and well-deserved reputation for the fantastic in scientific circles, has some small point. Consider whether your current theory and his are even mutually exclusive. Is this a case of either/or, or both?

Sincerely,

– M. Van Allen

I must agree with the idea that the primary relationship is with the predator. Not only is the snail’s location clearly marked for any with eyes to see, but so too is his path. And surely a creature who regularly preys upon these snails would be faster at discerning the direction it went than you, who merely stumbled upon it?

As to the idea that the snail would be more likely to take the mycoid to favorable locations… surely the predators of snails also frequent those locals? And likely several different ones over the course of a week? While a snail, on the other hand, is more likely to stay close to a single source of nutrition, as it takes so much longer for it to even search for another…

And have you considered that the snail itself may not be poisonous? Hiding beneath a toxic screen does not make it toxic of itself. I would assume that the regular predators know how to avoid the mushrooms in search of the tender flesh, if they have a problem with them at all.

Just the ideas that flow from the reading. Your works do spark a lot of thought. I look forward to seeing what is inspired by your next discovery.

My dear Dr. Roundbottom, I would like to add a conjecture of my own.

It strikes me as odd that your other correspondents have chosen to speculate primarily on the benefits a mycoid might glean from the carrier snail, and not the reverse. For surely a snail is a higher order of being than a lowly mushroom. As such, it is likely the author of this arrangement, evolutionarily speaking. Therefore one must ask, what does the Carrier Snail have to benefit from spreading poisonous spores willy nilly?

If you were to follow the snail for a longer period of time, you might find… in fact I will wager that you will certainly discover, that this particular species of gastropoda in fact feeds upon dead animals, such as the poor rodent that expired in your laboratory. Small mammals and birds are likely to feed upon mushrooms of this particular size and shape. I further hypothesize that the carrier snail perambulates in long looping circles, constantly crossing its older paths to feed upon whatever animals may have fallen in its wake.

This would explain why the mycoid glows. It is designed by nature TO BE EATEN, solely for the benefit of this particular species of gastropod. So, you may ask, doesn’t this cause danger to the gastropod itself, the illumination drawing predators to the snail itself? Well, that is the reason for the gastropod’s hard shell! Any animal attempting to eat it will ingest the soft mycoids on its back first, then expire rapidly, going instantly from predator to prey!

How then, you may ask, does the mycoid manage to reproduce if it is destined to be eaten? From your description, it seems to me that the reproductive stage of the mycoid’s live cycle is entirely enacted while still on the snail’s back. The spores which are let loose to grow, you might find, are incapable of reproduction! For if they did so, the lethal path of the snail would spread out, losing its structural integrity, making it less likely for the snail to encounter victims. No, it is necessary for this entire arrangement that the mycoids remain entirely in the path that the snail has laid for them.

If that is so, then the snail itself must provide the mycoid with some sort of substance that it requires in order to stimulate reproduction, perhaps excreted from the carrier snail’s shell. So your initial observation that these two species are utterly dependent on each other is true, but particularly for the mycoid, which could not reproduce without the snail. Although, for all we know the mycoids may play their own role in the snail’s reproductive cycle.

Of course, I could be wrong. But if you should happen to do further testing of this fascinating pairing, I would love to learn more. One must forever be a student, particularly us teachers.